Many of you have probably heard that Apple's operating system is famous for its reliability and the low number of errors and failures that occur during operation. However, Mac OS, unfortunately, is not perfect and one day it may simply not boot for no reason at all.

Without a doubt, this behavior of your Mac can be caused by a number of different errors, which need to be eliminated in different ways, but the author of this article has recently increasingly encountered a situation where MacBook won't boot after operating system update(Mac OS Sierra in this particular case) and makes three loud squeaks, repeated with a certain frequency.

Unfortunately, this can happen to any of us, and contacting a service center is often not timely and, of course, not cheap. Luckily, there's an easy method worth trying before you take your Mac anywhere. Judging by the reviews on foreign forums, it helped many people save money on using the service, and such a “hint” has helped the author of this article more than once. This is what we will talk about. So, what to do if your MacBook won't turn on?

Error appearing when booting Mac

As mentioned above, a computer can behave in a similar way due to a number of different errors (at least 4, judging by the help on the Apple website).

However, in our case, the sequence of actions and the patient’s symptoms look like this:

1. you have installed an update to the Mac OS operating system (or the computer installed it itself if you have auto-update enabled);
2. when you turned on (rebooted) your MacBook, instead of the expected operating system loading bar, you saw only a black (well, slightly gray, the side backlight of the monitor still turns on) screen;
3. Looking at this “light black” screen, you heard three long sounds like “beep-beep-beep”, repeated at intervals of 5 seconds.

Having carefully studied the official Apple website, we find the symptoms and description of our error:

"Three consecutive beeps, repeated with a five-second pause: RAM has failed the data integrity check."

Okay, I see, it's a RAM error on our MacBook. But the officials somehow forgot to offer any solution. But we found it, and it turned out to be as simple as shelling pears. Of course, it’s not a fact that this method will help you 100%, but it’s worth a try, because... for many it is works.

By the way, judging by discussions on foreign forums, the following MacBook models most often produce this error and do not turn on: MacBook Air a1466, MacBook Pro a1278 and a1260. It is from the first that we are writing this article.

Solving the problem - resetting SMC parameters

So if your MacBook Air, MacBook Pro, iMac, Mac mini or Mac Pro won't turn on and beeps- This indicates a random access memory (RAM) error, which can most often be resolved by resetting the System Management Controller (SMC).

Depending on what device you have, follow one of the algorithms below.

If you have a MacBook with a non-removable battery

And most modern models are like this, then the algorithm of actions for you is as follows:

If you have a MacBook with a removable battery

Although, in my opinion, these have not been produced for a long time, but just in case, we proceed as follows:

If you have an iMac, Mac mini, or Mac Pro

That is, one of Apple’s desktop computers, then resetting the system management controller (SMC) parameters is even easier:

Using the method appropriate for your Mac, you will most likely see the usual Mac OS loading window - this means that the problem is solved.

What does resetting SMC affect?

If you are not very knowledgeable about computers or are simply encountering such a procedure for the first time, then before performing the steps described above, a completely reasonable question may arise: “Will I lose important data or settings on my MacBook as a result of resetting, because this procedure is somewhat similar to "hard reset" on some gadgets?"

We hasten to reassure you - no, you will not lose anything important. If you are really interested, then take a look at the list of functions for which the system management controller (SMC) is responsible, the parameters of which we reset:

• response to pressing the power button;
• response to opening and closing the display lid on Mac laptops;
• battery resource management;
• temperature control;
• sudden motion sensor;
• ambient light sensor;
• keyboard backlight;
• status indicator control;
• battery status indicators;
• Select an external (rather than internal) video source for select iMac displays.

Alternative option - rearrange the RAM

If the option suggested above did not help and your MacBook still does not start, then you should try an alternative method. However, it is not suitable for any Mac computer, but only for those whose RAM can be replaced and not soldered on the motherboard (as is done in most modern Mac models).

If you have one of these computers, then this option may well help you, you just need to know how to get to the RAM slot. The algorithm of actions is very simple:

That's all. Now you know what you can try first if your Mac won’t start and beeps with a nasty signal. We hope that one of the options suggested above will help you solve this problem and save a significant amount of money on contacting a service center.

If suddenly, no matter what you do, your MacBook does not turn on, there is no need to rush to the service center. It is quite possible to try to “reanimate” it at home - the typical problems are known and they are quite easy to fix. The only exceptions are mechanical damage and flooding with any liquid, be it plain water, chemical liquid, alcohol or a sweet drink.

Another reason to immediately contact the service is the smell of burning and cotton.

Most often, the charger and power connector, the controller suffer, and less often - a short circuit and a system error. The most rare, but severe case is a crack in the motherboard or hard drive.

Eliminating display malfunction

First of all, you need to check the screen - perhaps the computer itself is fine, but there is a problem with the display.

How to check this:

• When you press the power button, you can hear the noise of the fan and disk drives;
• after pressing the power button you can hear the melody of loading the OS;
• if there are power/sleep indicators, they light up accordingly;
• If you press Caps Lock, the corresponding indicator will light up.

In this case, you need to check the operation of the display in accordance with the instructions on the Apple website or contact a service center.

Eating problems

What happens more often is that the MacBook stops turning on due to power problems.

If the computer does not turn on, then here is a simple check algorithm that needs to be performed:

• Is the computer connected to a power outlet? Is the socket working? it's easy to check.
• Are the power cord and adapter connected? ordinary forgetfulness and loose connections may be the reason for the lack of charge;
• Is everything ok with the power cord? if you have a spare or analog charger, it makes sense to try charging the mac with it;
• Are there any accessories connected to the computer (printer, storage device, phone)? turn them off and try pressing the power button again;
• After pressing the power button, hold it for 10 seconds and then press it again.

If these simple steps do not help, you will have to understand in more detail why the computer is not working.

No power supply

Most often, the problem is very simple and lies precisely in nutrition. Malfunction of the socket, uninterruptible power supply, or “pilot” occurs most often.

To check this, it is enough to connect a known-good device to them, and it is best to simply reboot the uninterruptible power supply. If you are using an extension cord, it makes sense to try connecting the power cord directly to the outlet.

It is also worth remembering that excessive use of extension cords, tees, surge protectors and additional blocks increases the load on the home electrical network and can cause a short circuit.

Charging does not work

Sometimes the reason lies in the charger. Kinks and pinching due to strong bending of the wire or pressing it, for example, by a door, render the power cord unusable. The most vulnerable places: bends of the cord, connection to the adapter, at the plug.

If everything is intact during a visual inspection, you should try to clean the connector from dust and at the same time check the integrity of the connector itself: bending or falling out of the plug means a complete malfunction of the power cord. This didn’t help either - it’s time to change the charger or go to a service center, they will definitely be able to diagnose the cause of the breakdown.

The battery has failed

If the computer is several years old, it may not turn on due to the fact that the battery life is exhausted. Usually it has an indicator that should light up while charging - if the charge is fully working, it makes sense to check this.

By the way, there are prerequisites for a battery failure - too rapid discharge recently, a discrepancy between the charge indicator data and the real operating time, and so on. In this case, the only way to fix your Mac is by replacing the used battery.

Video: Apple MacBook does not work

Reset settings

A special memory or controller error can also prevent your Mac from turning on. The fix is ​​simple, just a key combination and a reboot.

System Management Controller (SMC)

Sometimes the system management controller is to blame for the refusal to work; the situation can be corrected by resetting its parameters. To do this, with the power cord connected, you need to simultaneously press the combination “Shift” + “Control” + “Option” and the “Power” button. All buttons must be released simultaneously.

In this case, the light on the adapter either continues to light without blinking, or turns off - this is normal. After this reboot, you can turn on the computer.

PRAM and NVRAM (whatevertheyare)

A special section of PRAM/NVRAM can also create a power-incompatible error.

What to do then?

1. press the “power” button;
2. press and hold the “command” + “option” + “p” + “r” buttons until the gray screen turns on;
3. hold the buttons throughout the reboot and until the mac emits the boot tone again;
4. release the buttons.

Power Manager

If an error occurs during power supply (non-safe shutdown, emergency shutdown, short circuit), “Power Manager”, which does not allow you to turn on the Mac, can also be rebooted.

• first remove the battery;
• press the “power” button;
• wait a couple of seconds, release;
• insert the battery back;
• Press the “Power” button again. The computer should start booting.

Other reasons

There are many reasons why a MacBook won't turn on. This could be damage to the power supply circuit, soldering of the board, or simply the fact that it is clogged with dust and overheats. Even an incorrect shutdown can make subsequent startup almost impossible. But usually everything is much simpler.

Separately, it should be said about the loading error after the update - in this case, the MacBook turns on, but only until the gray screen or the loading screen does not complete.

MacBook won't turn on after update

If the computer has not been updated for a long time, and then you have to install fresh upgrades to the old version of the OS, the MacBook may not turn on or turn on but not boot.

Photo: gray screen during “eternal” loading

In this case, it is best to boot into safe mode - to do this, just turn on the Mac while holding down the “Shift” button.

Did not work out? Then you will have to format the data using a special utility; instructions for using it can be found on the official Apple website.

MacBook overheated

If the computer is several years old or it’s hot outside, then it’s not surprising that it refuses to turn on. Most likely it overheated. Under no circumstances should you apply cold objects to it or place it in a cold room; this can cause microcracks in the circuit boards due to temperature changes. After a couple of hours at room temperature, you can try to start it again.

If it is at least a year old, it makes sense to take care of cleaning it. You can do this yourself, if you have the necessary skills, or at a service center. But while the computer is under warranty, it can only be disassembled by a warranty service, otherwise free service will be impossible. Routine cleaning to prevent such problems is carried out at least once a year.

There are connected devices

An abundance of connected devices can draw power from your Mac's battery, preventing it from turning on. These are smartphones, tablets, external hard drives, flash drives, external Bluetooth modules, webcams, printers and other accessories.

There may also be errors in their operation that affect the launch. It's easy to check - turn off everything unnecessary and start the computer.

We do a forced reboot

If the computer shows at least some signs of life, you can try to force a reboot.

To do this, when connecting Magsafe power you need:

1. press the combination “shiftt” + “control” + “option” / “alt” + “power”.
2. if it's an old mac then use the combination "control" + "enter".

Video: MacBook Repair

Faulty north or south bridge

If the MacBook regularly overheats, then it may not turn on due to damage to the bridge - this is the controller on the motherboard. There are two of them, they are connected to the board by buses, and the northern one is directly connected to the processor. Damage to any of them requires a mandatory service call.

Only diagnostics by a specialist and replacement of the affected part will help here.

RAM module not installed correctly

If there was an OP upgrade before the problem, then perhaps the module was installed incorrectly. To check this, simply pull it out and reinsert it, checking the instructions. Did not help? Then return the old module as the new one may be faulty or incompatible. After this replacement, the Mac should turn on.

The reason why your MacBook won't turn on could be due to a variety of problems. It is best to find out what preceded the breakdown: unsafe shutdown, complete discharge, overheating, physical breakdown or flooding.

Even if everything seemed fine outwardly, it is better to ask your family or colleagues if they touched the computer, if there was a power outage, or if there was a strange smell. Depending on this, different methods of restoring work are used.

The only exception is mechanical damage and liquid ingress.

In this case, you should not try to solve the problem yourself, but it is best to remove the battery and take the Mac to a service center as soon as possible. Sometimes repairs may not be necessary - regular cleaning may well return the MacBook to working condition.

How I lost my main working tool during a trip.

About a month ago I went to Moscow for a couple of weeks to stay with relatives. And this should not have affected all areas of my activity, because they are tied only to high-quality access to the network and loved ones MacBook Pro 13''. There could be problems with the Internet, but the laptop has never let me down on a single trip. I didn’t even worry about him, and in vain.

Already on the second day in the capital I was left without my main means of production.

My advice is to beware of summer beaches and protect Mac from soft drinks.

Can you guess what happened to him? The guys from MacPlus, who were recommended by a local colleague, took this laptop for diagnostics, and at the same time shared information about the 5 most “popular” Mac defects. Next, based on our conversation, I’ll tell you what problems summer (and not only) can bring with it.

1. Cooling system malfunction

Overheating is often feared, but what exactly happens to your laptop when this occurs:

Despite the fact that the cooling system of any MacBook significantly superior to most competitors PC-solutions, it still needs to be cleaned at least once a year. Otherwise, it gradually becomes clogged with dirt and dust, which is why its performance significantly decreases over time.

The result will not be long in coming - serious overheating and failure of the motherboard elements is inevitable.

Nowadays you can often hear that preventative work - cleaning the cooling system and replacing thermal paste - needs to be done at a minimum once a year.

Of course, this indicator is actually individual and depends on where and how long you work at your job. Mac. If, for example, a laptop has been left switched off for 5-7 months (although this is hard to imagine), there will most likely be much less dust in it than in the same one, but actively used.

The fact is that dust gets into the cooling system through its own “fault”. The fan, removing hot air from the case, at the same time sucks dust from the environment inside.

Let us note once again that the indicators are individual - they depend on the working conditions, its duration and on the laptop model too. For example, a 15” MacBook Pro will get dusty much faster than the same MacBook Air.

It is worth mentioning separately about as thermal paste. Some of its types can easily withstand up to 140 degrees, while others have rather low threshold values ​​at which they cannot cope with the load. In this case, the entire required amount of heat is not transferred to the cooling system; some remains “on the chips”. This increases the load, the temperature goes beyond safe limits, and the resource in this mode is used up much faster.

In some cases, the dust itself not only contributes to heating, but can also become a conductor of current (of course, this does not happen often, but it is still possible).

With thermal paste, everything is also not so simple: it does not always dry out within a year. It all depends on what you do: permanent work in Final Cut or a game of Call of Duty will significantly speed up the process, and gentle use, on the contrary, will delay the problem.

But you still shouldn’t deviate from the rule: at least once a year you need to show your Mac to a specialist. If it is clean, they will tell you so directly. If cleaning is necessary, at first the laptop will simply turn off during operation or slow down, but you definitely shouldn’t wait until it refuses to turn on even after cooling down.

You can remove the cover and look at the condition of the device in a few minutes, but repairing devices that are already out of order is much more difficult. And more expensive.

2. Troubles with charging or power supply

It's not that simple; there are several options.

The battery has died

Here we need to highlight two equal options. Either the battery has exhausted its life and is not suitable for further use, or it was simply blocked by charge controller. Of course, the MacBook will not turn on.

There are many publications on this issue. We'll just reiterate the obvious: Mac batteries are very reliable, but they don't last forever, and sooner or later they have to be replaced.

Practice shows that this always happens unexpectedly. Of course, various utilities can now monitor the condition of the battery, and the system itself does this. But there is always a possibility that the battery will fail for no apparent reason: long-standing and already forgotten contact with moisture, unnoticed overheating or voltage drop, the “fault” of a low-quality charger.

In some cases, an unsuccessful attempt to charge the Mac may be recognized by the battery controller as physical problem. In this case, part of the circuit is specifically disabled - this is a protective mechanism. The battery cells themselves may be quite good, but the battery controller considers it “dead” or dangerous for the MacBook.

By and large, in such cases repair is possible, but it involves transferring the board with the controller from the donor battery to the one being repaired and “coordinating” them using a programmer. This is not possible for all battery models, but in cases where it is possible, the repair process is comparable in cost to replacing the entire battery. And the latter, of course, is much more reliable.

There are problems with the power connector

When using a laptop in a particularly hardcore mode MagSafe may fail for several reasons - the connector contacts are oxidized, covered with dirt or worn out. As a result, the MacBook battery is discharged to zero and the laptop does not turn on without recharging.

The situation with a faulty MagSafe is not uncommon. It can occur in almost any model, but most often it happens with Unibody models from 2008-2012. Now such Macs are no longer produced, but they are used quite actively. Considering the age of even the “freshest” 2012 model, during preventive maintenance it is necessary to clean not only the cooling system, but also the surface of the connectors.

The MagSafe connector is always open and the contact pad dust settles. It somewhat degrades the quality of the electrical connection, and frequent connections wear out the leads. Tenths of a millimeter are often enough to lose contact.

If contact is lost frequently, the MagSafe board begins to heat up, the battery may fail (the system perceives this as frequent connection/disconnection of the charger), and then the motherboard itself.

So, of course, you need to use high-quality power supplies. And keep the Mac itself clean.

The power supply is “covered”

Another reason for the inability to charge a MacBook is a non-working power supply, which could fail for a number of different reasons: from the same voltage drops to simple wear and tear.

At the same time, a “working” Mac may well recognize such a block. Over time, charging performance degrades. They are quite enough for the system to “see” the power supply and show the “battery is charging” status, but it will no longer be possible to charge a switched off and completely dead laptop with such a unit.

The situation is the same as when charging MacBook Pro 15″ block from Air. The process goes on, but much more slowly, and if the battery is completely dead or “went into protection”, a current of sufficient power is needed.

The block must be selected carefully. The point is not only in the quality of execution (the original or a factory copy has very good protection against various emergency situations), but also in compliance with the parameters - the power and current of the power supply must meet the requirements of the laptop.

You can use a more powerful charger - it is safe, but a weak charger (as mentioned above) is not recommended. In most cases, the Mac will simply charge slowly (for example, if it is turned off and not drawing power itself).

If you are working on a laptop connected to such a low-power unit, then the system thinks that it is charging, although in fact it is discharging, because during charging the battery receives less from the power supply than it consumes, and the indication on the battery icon will not tell you about this. The result is battery wear and failure.

3. Serious voltage drop

Motherboard components burned out

The worst thing that can happen during a power surge is failure of the motherboard elements. It involves a complete replacement or expensive repair of the MacBook.

Such cases are always the most difficult. The whole circuit or just one single element “burns out.” And the result is known - Mac shows no signs of life. With devices that have experienced a voltage surge, you need to be especially careful - the problems may be ambiguous and may not appear immediately.

For example, you have a completely working Mac, but discrete graphics does not work or does not turn on WiFi, although both the module and antennas are working.

The answer is not always on the surface, but recovery is just as real as, for example, when replacing a hard drive or other basic repairs. Such problems, as a rule, do not affect the durability of devices. And if they were eliminated, then Mac will work without problems.

Most often, “duty circuits” suffer - this is the name given to areas that are always under voltage, even if only slightly. “Power” elements operating under high currents are also at risk.

The battery is “covered”

Due to the large voltage drop, the MacBook battery usually goes into protection mode, but it can also “die” completely. This has already been discussed above.

The power supply died

A voltage drop very often causes the “death” of a power supply that fails completely or partially.

It is safer to replace such a block, because if it saved Mac- it's worth it.

4. Heavy and prolonged load

Chipset or video chip burned out

MacBook can cope with a very large and prolonged load, but only with a working cooling system that is regularly cleaned. Otherwise, it will overheat greatly, which will cause its “death”.

To be more precise, not only the chips themselves can fail, but also the “piping” - auxiliary elements that distribute power to the chips.

The video chip (also known as the graphics processor) is the main element, the “heart” of the video card. In modern Mac this chip is located on the motherboard.

The chipset is also part of the motherboard, and in some models it also includes a graphics processor. Plus the chip performs many other important functions. But even if all the chips “survived,” the problem may still appear.

Overheating may cause contact failure BGA- leads of the crystal itself and landing spots on the chip substrate (mirror square and PCB square with elements soldered onto it).

Even more often, and even in the overwhelming majority of cases, the crystal lattice itself fails. Temperature changes its structure, and the chip must be replaced. In this case, the problem can be temporarily solved by heat shrinking the chip, which makes it possible to partially restore the structure of the crystal lattice or return the crystal-substrate contact.

But, as a rule, when the graphics fail, the chip needs to be replaced with a new one, and the technique itself serves more for diagnostic purposes.

The chip almost always fails under overloads, especially long-term ones. There are many options here: you can “burn” your Mac in exciting gameplay, leave it overnight to edit a video, or render a large project.

A clean cooling system will help here, but it is also not all-powerful. Particularly difficult Mac cope with overloads Windows, at least previous versions (maybe also because there are much more demanding games for this operating system than for OS X).

5. The device was filled with liquid

Keyboard failed

The keyboard is the first thing that suffers when it hits MacBook liquids. In this case, it may fail completely or partially. If the power button fails, the laptop simply cannot be turned on. Interestingly, this may not happen immediately, but rather a long time after the incident.

Therefore, it is cheaper and more reliable to strictly follow the rule: Fill up your MacBook - go to the service center, even if everything is fine, especially since diagnostics can be done for free in any case.

The keyboard is one of the most vulnerable places in Mac. The easiest way to fill it is. Often it dries up and works, but even then it is at risk and may someday suddenly fail.

The fact is that the keyboard itself has a flexible transparent substrate on which tracks are laid out for each key. They are the ones that oxidize. Technically, the keyboard can be repaired, but given the labor costs, such work will cost almost the same as replacing it with a new one.

Often the keyboard backlight “saves” everything else - a small amount of moisture penetrating through the keyboard is blocked by the backlight (it is glued to the keyboard quite tightly and is equipped with a thick film on the back side). This is exactly what happened with my Mac.

Short circuit on the motherboard

If liquid gets on the motherboard, a short circuit may occur immediately or over time. It's all due to oxidation of contacts.

Approximately 40-50% of devices that are repaired are flooded or have ever been flooded. Let us once again draw attention to what has already become a well-known fact: contact with moisture will not pass without a trace for almost any device, no matter Mac This, iPad or iPhone.

Oxidation almost always occurs very quickly, especially if you do not physically disconnect the battery from the motherboard. It is simply necessary to do this, but most owners of modern equipment are unlikely to have a screwdriver with such a favorite Pentalobe, which is now used in almost all new Mac.

Simply turning off the laptop is not enough; power is still supplied to the board, and the liquid that gets on it acts as an electrolyte. The result is a homemade battery - the electrolysis reaction is started, its products appear on conductive elements and tracks, and especially small components can be completely destroyed in the process.

Therefore, if you have a suspicion, or you know for sure that water has gotten inside, you should not put off repairing your MacBook. At least you need to check the condition. Again, it’s better to play it safe and contact us as soon as possible, when the damage is still small, because the further you go, the more difficult it is to bring your Mac back to life.

Sometimes the tracks themselves have to be restored. Particularly difficult is moisture under the microcircuits. They are not sealed to the board, but the microscopic gap is enough for water to get in.

Cleaning in an ultrasonic bath in industrial alcohol solves two problems at once - moisture is removed from hard-to-reach places (water is heavier than pure alcohol), and ultrasound allows you to remove oxides from the surface.

It is also worth noting here that water itself is not so dangerous for electronics, but from experience, almost everything that gets into Mac– aggressive environments – soda, coffee, sweet tea, alcohol and so on. If the board is disconnected from the battery and the unit, electrolysis proceeds much more slowly, but in practice the battery is almost always connected.

And let's repeat it again. Even if immediately after the incident everything is fine with your computer (at first glance), the equipment is still worth inspecting, because the problem may appear much later, when you have already forgotten about what happened. And, as practice shows, restoring such laptops is much more difficult (and not always possible).

All's well that ends well - that's for sure

As it turned out, without my knowledge MacBook Pro filled with something like "Mojito" summer on the beach almost a year ago. The liquid was hastily wiped off the case, but it got inside. In the end, the keyboard contacts oxidized, and the power button simply did not work. The keyboard was completely replaced and the laptop came back to life. It's good that the cocktail did not reach the motherboard.

While I was drinking coffee and talking with MacPlus specialists, they managed to check the laptop for other problems that were not identified. He escaped with little blood.

How has your Mac ever let you down?

P.S.: For those who are experiencing problems, we offer battery replacement ( 3.60 out of 5, rated: 5 )

website How I lost my main working tool during a trip. About a month ago I went to Moscow for a couple of weeks to stay with relatives. And this should not have affected all areas of my activity, because they depend only on high-quality network access and my beloved MacBook Pro 13’’. There could be problems with the Internet, but the laptop...

When you hear a squeak, there is clearly a problem with the system. If your iMac fails, it is always perceived as an unfortunate failure: the system works, but the background sound quickly causes fatigue and affects your well-being.

Tolerate this?! In no case!

What causes a squeaking sound when using an iMac?

• Distortions and malfunctions in RAM, cooler/fan,
• Hard drive failure;
• Microchip malfunction,
• Firmware update required.

Squeaking is not a typical phenomenon when the iMac is operating, and if you do not pay attention to it, the iMac will begin to overheat or one day it will not turn on at all. This will damage the processor and video card. Don't make the problem worse! It's better to make do with small losses.

Sometimes your iMac makes intermittent sounds or a prolonged squeak. The most obvious thing is that the device is clogged. Under a large layer of dust, the fan begins to “sound” because the cooler blades come into contact with dust layers.

In addition to cleaning it, it may be necessary to change the thermal paste. It is a gel-like substance, the main purpose of which is to cool the internal components of the aimak. When it dries out, the heat distribution is distorted, and then the iMac overheats.

Our company offers high-quality thermal pastes from Apple - Microsi and Keratherm. They perfectly cool the processor and the entire system as a whole. But you can decide what exactly needs to be done only after professional diagnostics of your iMac. Our specialists spend no more than 30-40 minutes.