The computer does not start, the fan spins up and stops. What should I do if the fans start and stop when I turn on my computer? Clear signs of trouble

In the life of almost every user, there have been situations when a computer or laptop suddenly began to behave differently than before. This can be expressed in unexpected reboots, various interruptions in operation and spontaneous shutdowns. In this article we will talk about one of these problems - turning on and off the PC instantly, and we will try to solve it.

There can be quite a few reasons for this PC behavior. These include incorrect cable connections, careless assembly, and failure of components. In addition, the problem may lie in some operating system settings. The information that will be given below is divided into two parts - problems after assembly or disassembly and failures “from scratch”, without outside intervention in the computer hardware. Let's start with the first part.

Reason 1: Cables

After disassembling a computer, for example, to replace components or clean dust, some users simply forget to reassemble it correctly. In particular, connect all cables in place or connect them as securely as possible. Our situation includes:

Reason 2: Short circuit

Most power supplies, including budget ones, are equipped with short circuit protection. Such protection turns off the power supply in the event of a short circuit, the reasons for which may be the following:

Reason 3: Sudden increase in temperature - overheating

Overheating of the processor during system startup can occur for several reasons.

• A non-working fan on the cooler or a disconnected power cable of the cooler (see above). In this case, when starting, it is enough to monitor whether the blades are rotating. If not, you will have to replace or lubricate the fan.
• Incorrectly or crookedly installed CPU cooling system, which can lead to incomplete contact of the base with the heat spreader cover. There is only one way out - remove and reinstall the cooler.

Reason 4: New and old components

Computer components can also affect its performance. This is either simple carelessness when connecting, for example, an old video card or RAM modules, or incompatibility.

Reason 5: Dust

The attitude of users towards dust is often very frivolous. But this is not just dirt. Dust, clogging cooling systems, can lead to overheating and failure of components, the accumulation of harmful static charges, and at high humidity it even begins to conduct electric current. What this threatens us with is discussed above. Keep your computer clean, not forgetting the power supply (this often happens). Clean from dust at least once every 6 months, or better yet, more often.

Reason 6: Power supply

We have already said that the power supply “goes into protection” in the event of a short circuit. The same behavior is possible if its electronic components overheat. The reason for this may be a large layer of dust on the radiators, as well as a non-working fan. Insufficient power supply will also cause a sudden shutdown. Most often, this is a consequence of the installation of additional equipment or components, or the advanced age of the unit, or rather, of some of its parts.

In order to determine whether your computer has enough power, you can use a special calculator.

You can find out the capabilities of the power supply unit by looking at one of its side surfaces. In column "+12V" The maximum power for this line is indicated. It is this indicator that is the main one, and not the denomination written on the box or in the product card.

It is also impossible not to mention the overload of ports, in particular USB, with devices with high energy consumption. Interruptions occur especially often when using splitters or hubs. Here we can only advise you to unload the ports or buy a hub with additional power.

Reason 7: Faulty hardware

As mentioned above, faulty components can cause a short circuit, thereby triggering the power supply protection. It could also be a failure of various components - capacitors, chips, etc., on the motherboard. To determine the faulty hardware, you need to disconnect it from the motherboard and try to start the PC.

Example: turn off the video card and turn on the computer. If the launch is unsuccessful, we repeat the same with the RAM, only you need to turn off the strips one at a time. Next, you need to disconnect the hard drive, and if there is more than one, then the second one. Don't forget about external devices and peripherals. If the computer does not agree to start normally, then the problem is most likely with the motherboard, and it should go straight to the service center.

Reason 8: BIOS

BIOS is a small control program written on a special chip. With its help, you can configure the parameters of motherboard components at the lowest level. Incorrect settings can lead to the problem we are currently discussing. Most often, this is setting frequencies and (or) voltages that are not supported by components. There is only one way out - reset the settings to factory settings.

Reason 9: OS Fast Startup Feature

A quick startup feature present in Windows 10 and based on saving drivers and the OS kernel to a file hiperfil.sys, may lead to incorrect computer behavior when turned on. This is most often observed on laptops. You can disable it in the following way:

Conclusion

As you can see, there are quite a lot of reasons causing the problem under discussion, and in most cases its solution takes a sufficient amount of time. When disassembling and assembling a computer, try to be as careful as possible - this will help avoid most of the troubles. Keep your system unit clean: dust is our enemy. And the last piece of advice: do not change the BIOS settings without prior information preparation, as this may lead to the computer not working.

The computer won't turn on in different ways - it may not boot, the power supply may not work, it may buzz, but the screen is black. This article will help you find the cause of the breakdown yourself, possibly repair it or find out what is faulty and estimate how much it will cost.

So, we will consider the following situations when the computer does not turn on as a test:

The computer does not beep, the fans do not spin, the screen does not turn on.

Most likely a breakdown power supply(BP). Press the power button and listen to see if the power supply fan is humming. If yes, look at the next point, no, spin up the system unit. I warn you right away - in the power supply itself the voltage is 220 V, but it is closed (such an iron box at the top of the system unit), and everywhere in the computer in the system unit the voltage is no more than 12 V - safe for life - you can safely twist and touch everything with your hands.

We move all the connectors and try to turn them on. If not, then pull out the power connector and short-circuit the contacts, as shown in the photo.

This is how we manually start the power supply. Usually these are green and black wires, but once I came across it was purple and black. If you look at the connector when the latch is on the left, then these are 3, 4 contacts from the bottom in the left column. If the power supply does not start, then you need to replace it ($25).

If it starts, you need to check the power button. We look for the wires going to the power button, pull out the chip labeled PW SW and short-circuit the pins with a screwdriver as in the photo.

If it starts up, you need to check and change the button; if not, the problem is in the motherboard: you need to take it to a service center or buy a new one.

The computer does not turn on, does not beep, the fans are spinning and the screen does not show.

This means 99% that the power supply is working. In some motherboards with a built-in video card, this happens if the RAM(RAM). Therefore, we take out the RAM, inspect it, clean it from dust and insert it back. We do the same with the power connector. We also remove and clean the video card.

We put everything back. Let's try. If computer won't boot and it doesn’t beep, but the coolers are spinning - the motherboard won’t start. There may be no power to the processor. All we can do is inspect the processor power capacitors. These are aluminum barrels near the processor.

They look normal in the photo. And sometimes they swell - there is a ghoul on top and the motherboard may not work. The solution is to take it to the service center or buy a new one. But if the PC still doesn’t work, then you can try clear BIOS settings.

To do this, look for a chip on the motherboard with the signature CLRCMOS and short-circuit it for about half a minute with a screwdriver.

If it doesn’t help, take the mother to the service center or buy a new one ($50).

The computer does not boot, does not beep, blue screen.

To begin with, as in the previous case, we try to clear the BIOS settings. It didn’t help - we try to change the cables from the DVD-ROM and hard drive (HDD), if possible. Pull out and reinsert all connectors. Sometimes a blue screen appears even when Windows crashes, then we try.

The computer does not turn on, something is written on the screen

If the computer beeps and does not boot

Squeaks are special BIOS codes. From them you can find out what is not working. But to do this you need to know what brand your BIOS is from. To do this, look for a shiny sticker with the word BIOS on the motherboard.

The photo above shows the BIOS from AMI. There are more of them than anyone else. We look at the decryption of BIOS signals.

We look at the signals to see what’s wrong with us.

I wish you that everything is in order with your iron. with you.

Misunderstanding of the nature of certain computer problems often leads to diagnostic errors, without which qualified repairs are impossible. And you should approach the search for a problem with its accurate description. A malfunction that is described with the words: “when you press the power button, the computer does not turn on, but the fans work” is called a lack of initialization or an initialization error. It should not be confused with “non-powering” - complete inaction when pressing power, since the causes of these two problems are usually different.

Initialization, in this case, is the readiness of the equipment for operation. And if any of the devices critical for starting the PC refuses to start, we will observe a characteristic picture:

• after turning on the system unit, a loud noise from the fans is heard (they rotate at a constant high speed);
• The keyboard and power indicators come on and do not go out;
• the screen remains black.

Nothing else happens.

Reasons

According to statistics, the most common source of such a problem is the following:

• damage to the BIOS - a program stored in the CMOS flash memory chip on the motherboard, responsible for the initial boot of the PC, as well as for checking and consistency of operation of all its devices at the startup stage;
• a failed processor or a malfunction of its power supply system;
• inoperability of RAM (random access memory) or incompatibility of installed RAM strips with each other;
• malfunction of system logic chips (chipset) on the motherboard, especially often the north bridge.

Other reasons that can also cause such a “clinic” include damage to the components of the motherboard, leading to destabilization of the device’s power supply, a defect in the solder contacts of the microcircuits, a power supply with voltage “drop” along individual lines, a dead CMOS battery, as well as other problems equipment installed on the PC. However, this is less common.

It is also important to understand that this problem is never the result of software glitches in the operating system. Because its download doesn't even start.

Diagnostics

What can a user do if he finds himself in such a situation? Even without special equipment, you can try to solve the problem at home. It is enough to know how to use a screwdriver.

Resetting BIOS settings to factory settings

This is the simplest and, sometimes, very effective way to troubleshoot computer boot problems. If your case is not the most difficult, perhaps it will help.

• Turn off the computer's power and remove the system unit cover.
• Find the coin cell battery on the motherboard and remove it from the socket.
• connect the contacts of the battery socket to each other, for example, using a screwdriver;
• reinstall the battery.

There is another option for resetting the BIOS - using a Clear CMOS jumper. It must be removed for 15 - 20 seconds. and move it to two adjacent contacts, and then return it to its place. Sometimes the jumper is called differently: CL_CMOS, CCMOS, CLRTC, CRTC, etc.

After completing these operations, connect the power to the computer and try to turn it on. If the problem is resolved, its cause lies in an incorrect BIOS Setup configuration.

Disable everything unnecessary

If the first method does not help, move on. Let's try to exclude the influence of equipment that is not necessary for a successful start of a PC. To do this, you need to prepare a table covered with insulating material (polyethylene, rubber, plastic, wood, etc.) on which you will assemble the stand.

Let's get started:

• turn off the power to the PC and remove the case cover;
• remove expansion cards from the slots of the motherboard, disconnect the power and interface cables from it, remove the memory sticks;
• remove the motherboard from the case, place it on the table and inspect for artifacts - swollen capacitors, signs of overheating (darkening and deformation of plastic parts), mechanical damage and other defects;
• if there are no artifacts, install one memory stick in the slot, connect a video card (if there is no built-in one), a monitor, a previously removed boot hard drive and a power supply;
• turn on the power supply to the mains;
• use a screwdriver to close the contacts of the power button - Power Switch (can be labeled as ON, PWR_ON, PC_ON) - this action is similar to turning on the computer by pressing this button.

If you see the operating system loading on the monitor, it means that the failure is caused by one of the disconnected devices. Well, if nothing happens besides the rotation of the fans again, let’s try to figure it out in more detail.

• Start the system. Carefully touch the processor heatsink and large board components - microcircuits, mosfets, etc. - normally they should be warm. Strong heating (don’t get burned!) indicates a malfunction of the elements (soldering defect, short circuit), and a complete lack of heating (room temperature) most likely indicates that the unit is not receiving supply voltage.
• Turn off the power to the PC. Remove the memory stick, remove the oxide layer on its contacts by rubbing it with a school eraser, blow out the slot where it was located, and install it back. Turn on your computer. If the problem is solved, the reason was poor contact between the RAM and the board connector. If it doesn't work, install the bar in another slot - it might be the culprit.

We replace components with known good ones

None of the methods helped? The last thing left that can be done at home is to replace PC devices one by one with working ones, of course, compatible with your system. However, there is a risk of damaging them.

If this is not possible or desirable, or if the described problem occurs on the laptop, the only remaining option is to contact a service center.

In diagnosing computer problems, many phenomena and connections are not obvious. That is, completely different faults have the same external signs. Surely many of you have encountered this form of PC “strike”, in which its operation continues... for just a few seconds. In other words, switching on is followed by immediate switching off, and at the same time there is a black “Malevich square” on the screen.

Let's talk about the reasons why a computer turns on and off immediately, and also what to do about it at home without special equipment.

Reasons for instant PC shutdown after startup

Traditionally, computer problems are divided into hardware and software. The former are caused by hardware failure, the latter – by the operating system and applications. The situation that we are considering today completely belongs to the first category, that is, it is always associated with hardware.

What could cause it:

• Unstable voltage in the household electrical network if the system unit is connected directly to it.
• Faulty power supply, broken power cord.
• Incorrect connection of any device inside the system unit - incomplete installation in the connector, contacts coming out, etc.
• Incorrect installation of the cooling system (the base of the radiator does not come into contact with the surface of the processor) or its complete failure.
• Short circuit in any of the devices in the system unit.
• Damage to BIOS firmware.

As you can see, the range of possible culprits is quite wide. In fact, anything can be the cause. An anamnesis (history of the occurrence of a malfunction) and the accompanying “clinic” will help simplify the diagnosis.

Narrowing down the search

First of all, you should find out what events preceded the current situation. For example:

• The computer began to turn off after a power surge. The likely cause is a failure of the power supply, sometimes together with other equipment connected to it.
• The problem occurred during a thunderstorm after a lightning strike somewhere nearby. The reason is electrical damage to the network controller of the motherboard.

• The PC stopped working after cleaning it from dust or replacing/connecting new equipment. Possible reasons are incomplete or incorrect installation of devices in the connectors, bent processor legs (if you removed it from the socket), incorrect installation of the cooling system, or an unconnected cooler.
• Before the problem occurred, you updated the BIOS, but did not complete the update (the computer rebooted, turned off, etc.). The culprit of the problem is a crashed BIOS firmware.

Next, let’s pay attention to the accompanying manifestations. For example:

• When you try to turn on the computer, you smell a burning smell, smoke appears, and the circuit breaker in the electrical panel knocks out. Most likely the power supply has failed.
• The computer turned off spontaneously with a loud bang. An electrolytic capacitor on any of the devices inside the system unit has exploded.
• When you turn on the PC, the cooler makes 1-2 turns and stops. There is a short circuit in the devices, incorrect or incomplete installation of equipment in the connectors.
• Cyclic reboot immediately after switching on (the cooler makes 1-2 revolutions, stops, then starts again, etc., repeating the cycle of starts and stops endlessly). Apparently the BIOS firmware has crashed.

The system speaker (buzzer) can provide valuable information about the source of the failure if it is soldered to the motherboard or connected to it separately. Sometimes in such cases he manages to give a sound signal, which indicates the culprit.

Probable cause found. What to do next?

If the diagnostic steps described above have led you to think about a malfunction or problems with the installation (connection) of a particular device, the next step is to confirm this version. As you might guess, it consists of inspecting connections - inspecting cables, connectors and sockets, checking the reliability of holding the device in the connector, test installation in another slot, etc. And if a breakdown is suspected, replacing the device with a known working analogue.

The following speaks in favor of connection defects:

• Darkening and melting of plastic connection elements (slots, connectors).
• Bent, shorted, broken contacts.
• Visible cracks and bends in cables.
• Loss of contact when touching the device or vice versa - the computer works while you hold the connected connector or device with your hands, and when you release it immediately turns off.

A device malfunction is indicated by:

• Visible defects of the elements - chips, burns, swollen, burst, leaking, electrolytic capacitors rusted at the base, etc.

• Local change in PCB color (usually appears on the back of the board under the faulty component), soot.
• Rapid and noticeable heating of any element on the device board when power is connected. In some cases, faulty components heat up even in standby mode - before pressing the power button on the system unit.
• Visible dysfunction. For example, the hard drive does not spin up, but makes a grinding or knocking sound, the cooler rotates intermittently or does not rotate at all, etc.
• After physically disconnecting a suspicious device, the computer stops turning off spontaneously.

At least one of the listed signs indicates a malfunction. At the same time, their absence in no way indicates the opposite. Very often, damaged devices do not have visible defects.

If the power supply turns out to be faulty, do not try to test it by connecting it to normally operating equipment; this will most likely damage the latter.

Also, do not try to disassemble the power supply. Accidental contact with high-voltage components may result in electric shock, even when the device is unplugged.

The culprit has not been found, there are no suspects

Often, failures like ours occur spontaneously - for no apparent reason and against the background of normal computer operation. The user has no suspicions about the failure of any specific device. More precisely, all hardware is under suspicion. What to do in such a situation?

Let's start with something simple. Without opening the PC case, unplug it from the outlet or press the power button on the power supply.

Next, press the power button of the system unit and hold it for 20-30 seconds. After that, connect the power and try to start the PC as usual. If the problem is caused by the accumulation of static or residual charge of capacitors, the next start will proceed normally and the failure will not in any way affect the further operation of the computer.

If this measure does not bring results, . There is a separate article on this topic, so we won’t go into details on how to do this. To reset, use the Clear_CMOS jumper or a coin cell battery, which is usually located near the jumper.

Perform further steps one by one, moving on to the next one if the previous one does not help. After each manipulation, try to turn on the PC.

• Disconnect all peripheral equipment from the computer, leaving only the keyboard and monitor.
• Visually inspect all internal devices and communications of the system unit, without disconnecting anything yet. Make sure the connections are secure and tight.
• Observe the behavior of the CPU cooler and case fans when you press the power button. Jerking and stopping, as stated above, is a typical symptom of a short circuit. Cyclic spin-ups and stops most often indicate a BIOS crash. A complete lack of rotation means problems on the 12 V power line, failure of the fan itself, or a failure in the control of the cooling system.

If the probable cause of the malfunction is a failure. Many modern motherboards allow you to do this without a programmer.

If the probable cause is a short circuit:

• Disconnect all equipment from the motherboard that is not necessary to turn on the computer. Leave the processor, cooling system, memory (one module is enough), video, keyboard and power supply connected. If the problem persists, the culprit is among the remaining devices.
• Check it out. In the event of a short circuit in the load (powered equipment), the switching power supply switches off in an emergency. This way they protect themselves from overload, which is caused by excessive current consumption.
• After determining that the power supply is working, remove all remaining hardware from the PC case. This must be done for two reasons: to prevent the motherboard from shorting to the case (occurs when the system unit is assembled incorrectly) and to inspect the devices from all sides in good lighting.

• Inspect the equipment for defects as described above. If you identify obvious signs of failure, replace the problematic device with a compatible analogue.
• Assemble a stand of devices on a table, connect the power supply and check for hot elements on the motherboard and video card. If there is, you have found a problem node. If not, start the stand by closing the contacts of the power switch on the mother. Where exactly they are located on your model can be found in its description.

Further troubleshooting of the computer, which turns on and immediately turns off, can only be continued by alternately replacing the remaining hardware, in particular, memory and video sticks. Although, if you have reached this stage, the most likely culprit of the problem is the motherboard. You can, of course, not stop there and move on to diagnosing this particular device, but we agreed to make do with our bare hands. Direct hands plus knowledge are your main assistants in solving any PC problem. The rest is secondary.