Having problems with desktop computer there may be various reasons. By following our advice, you can quickly fix any problem.

PC failure can manifest itself in different ways. For example, after pressing the power button, the machine shows no signs of “life”. Or the computer turns on, but individual components are not functioning. The first step is to figure out what actually works and what doesn’t. Are the motherboard LEDs on? Are the fans spinning? Is the monitor receiving an image signal? Are BIOS messages displayed? Based on these observations, most problems can be classified into six categories (see below). For each category, we provide instructions consisting of sequential steps with which you can eliminate the possibility of simple faults, so that you can then proceed to more complex diagnostics. If you are not successful at any step, move on to the next one until you solve the problem. Even if you stop at some step, the results of your testing will subsequently become a good help for the service center employees.

1. No signs of life

If the computer does not respond in any way when you press the power button, you should first check the power supply or the button itself. We will help you localize the problem.

1.1. VISUAL INSPECTION. First of all, check if the power cord is well connected and turned on. network filter. It is possible that the power supply button on the back of the computer is in the “Off” position.

1.2. CASE CONNECTORS. Open the PC case and check that the connectors are securely connected and that the cable is not damaged in the area between the switches and LEDs of the case and motherboard- perhaps some connector has come loose from the plug. If one or more cables are disconnected, open your motherboard manual and check to see if the cables are properly connected to the plugs.

1.3. POWER BUTTON. If the chassis connectors are connected correctly or reconnection did not bring results, disconnect all connectors from the motherboard. Then short the two contacts labeled "Power Switch" using a paperclip. If the computer turns on, there are two options. First - faulty button inclusions on the body. In this case, you need to connect both connectors labeled “Reset Switch” to the contacts labeled “Power Switch” on the motherboard. From this moment on, the PC will be turned on using the reset button, and the power button will no longer perform its function. Another reason for such a malfunction may be a short circuit in the reset button: a regular button in this case will not work, and starting the PC will only be possible by shorting two contacts on the motherboard. This assumption will be confirmed by the ability to start a PC with the reset button disabled. In this case, leave the power button connected and disconnect the reset button. After all these steps, your PC will most likely turn on again without any problems. If even when using an office paper clip the computer refuses to “start”, then you should check the power system.

1.4. MOTHERBOARD POWER SUPPLY. Check that all power supply connectors are correctly connected to the motherboard. It's about not only the wide 24-pin ATX connector, but also an additional four-pin P4 connector for powering the processor.

1.5. POWER UNIT. Next, you need to exclude the possibility of failure of the power supply. To do this, connect a working power supply to the PC - for example, from a second computer. Connect the 24-pin ATX connector and the four- or eight-pin P4 connector of the working computer to the motherboard of the faulty PC and try to start it. If after this it turns on, then the whole problem is in the power supply, which will need to be replaced.

1.6. MOTHERBOARD. If all the measures described above did not help, then most likely the motherboard, which is best replaced, since repairs not under warranty, as a rule, are not worth it. One way or another, replacing the motherboard means complete disassembly and assembling your PC. But it is recommended to proceed with this procedure only if other possible malfunctions have been excluded.

2. PC works, but no image

After turning on, the screen remains black, although the power supply, CPU and video card fans are running and the LEDs on the motherboard are lit.

2.1. CHECKING THE MONITOR. The first thing you need to do is rule out a trivial malfunction by answering the question: does the monitor turn on? If not, there may be a power problem: the cable is unplugged from the display or wall outlet, or the screen has a switch that is set to the Off position. If the monitor turns on, open the OSD menu and check if the input source (VGA/D-Sub, DVI, HDMI) is selected correctly.

2.2. SOUND AND LIGHT SIGNALS. If the monitor is not receiving an image signal, the motherboard will often let you know by sending beeps or lights to help you figure out what the problem is. Consult your motherboard manual to determine what the signals mean. One of the typical defects reported in this manner may be faulty or incorrect installed modules RAM, which the motherboard, depending on the model, warns about with sound signal or burning LED lamps.

2.3. RESET BUTTON. Short circuit The reset button may also be the cause of the above symptoms. Perform the check (point 1.3).

2.4. BIOS. Sometimes the reason similar problems with the launch there may be incorrect settings BIOS. To reset BIOS settings, find the Clear CMOS jumper on the motherboard. We are talking about three contacts, two of which are connected by a jumper. Remember initial position jumper, then pull it out and connect another pair of contacts with it, wait at least ten seconds. After this, set it back to its original position. If the system board has a reset button, press it. If the computer turns on, check BIOS settings. In most cases, you need to select the correct operating mode of the SATA controller, which, starting with Windows XP, is “AHCI” and not “IDE”. After that stated problem must disappear. One of possible reasons If the BIOS settings are lost, the motherboard battery may be dead - this will be discussed in paragraph 3.1.

2.5. RAM. ABOUT faulty memory Most motherboards signal using sound or light (LED) signals (see paragraph 2.2). However, we recommend checking the functionality of the modules random access memory without waiting for a warning signal. There must be at least two modules installed in the computer - remove one and try to boot the computer with it. If the PC does not turn on with this module, try starting the system with another module installed. If the computer starts with only one memory module, this usually means that the other one is faulty.

2.6. VIDEO CARD. Among PC components, the problem should first of all be looked for in the image signal source - graphic card. If your computer has an integrated graphics card, remove the discrete card and test the system with the integrated GPU. Otherwise, check if the PC works with a different graphics card. If yes, then your discrete or integrated video card is faulty.

2.7. CPU. A faulty processor can also be the reason why the computer works but does not produce an image signal. Therefore, if possible, test the performance of your PC with another compatible processor before the next very difficult step.

2.8. MOTHERBOARD. Due to the fact that everyone else possible sources problems have now been ruled out, the last “suspect” remains the motherboard. The problem here could be, for example, in the CMOS chip in which the BIOS is stored, or in the PCIe bus to which the video cards are connected. Troubleshooting in most cases does not pay off, so the best solution will immediately replace the motherboard.

3. BIOS stops working

The BIOS's job is to prepare the computer to boot operating system. If in progress BIOS operation When problems arise, error messages will usually appear that will help you localize them.

3.1. BIOS SETTINGS. With computers released four or five years ago, situations often occur when they suddenly refuse to boot. The reason lies in the BIOS settings. In this case, the message “Please enter Setup to recover BIOS setting | CMOS Date/Time Not Set." You can usually enter the BIOS using the “F1” or “Del” button when you turn on the PC. After this, you need to restore all the basic settings - for example, date, boot device sequence, or such important parameter, as the operating mode of the SATA controller (AHCI). After restoring the settings, there should be no problems booting the PC. However, the reason that the settings were lost most likely lies in the following: there is a round flat-plate battery on the motherboard, which is an “emergency” power source for the CMOS chip so that the latter does not lose the settings. If this battery has run out, it needs to be replaced, otherwise the BIOS settings will be lost every time you turn off the PC.

3.2. BOOT DEVICE SEQUENCE. If the BIOS reports that it cannot find bootable media, then there may be several reasons. First, check the boot device sequence in the settings. In modern motherboards, this requires two operations. In the boot options you will find the item “Boot priority”, which lists components such as hard disks, removable media or optical drives. HDD must have the highest boot priority.

3.3. DISK FAILURE. If the drive does not appear in the media selection menu in the BIOS, open the PC and check that the power cables and interface cables of the corresponding media are securely connected. If the problem is not solved, test the drive with a different cable, in a HDD enclosure with USB interface or on another computer. If this does not help, then most likely the media has failed as a result of damage to the controller. In this case, most likely only a specialist will be able to recover the data at a considerable cost. If you regularly create system images and backups data, then you will only need to replace the disk and copy the data. Otherwise you will have to complete reinstallation systems.

3.4. LOAD SECTOR. If boot device appears in the BIOS and you can view its contents when connected to another PC, it is most likely damaged boot sector. This happens quite often when a redistribution attempt fails. disk space or when Linux removal, used as a second operating system. To resolve the error, boot from the installation DVD or disc disaster recovery. During the boot process, select “Repair your computer” or “PC recovery options”, then click on “System Restore”, and then follow the wizard’s instructions. If this does not solve the problem, then try restoring manually. Boot your PC again as described above, and in the system recovery settings, open the window command line. Enter the following commands in it:

bootrec /fixmbr bootrec /fixboot

bcdedit ;/export C:\bcd_1 c: cd boot attrib bcd -s -h -r ren bcd bcd_2 bootrec /RebuildBcd

After this, Windows should boot. If you still have difficulties, follow the instructions below.

4. OS cannot boot (Windows logo appears, but system does not start)

Your computer starts to boot, but just before the user interface"freezes". With such symptoms, you can rule out many problems with the hardware and BIOS.

(to be continued)

A local network is a mechanism whose operation depends on external factors: power supply stability, quantity and quality installed programs, hardware computers, protection from external threats etc. Each of them can cause unstable work or refusal local network.

To diagnose and eliminate such failures, Windows 7 provides a fairly effective standard mechanism. To launch it, go to Start > Control Panel. Network and Internet >> Network and Control Center shared access>> Troubleshooting - a corresponding window will open.

In this window, select one of the following diagnostic and troubleshooting modes.

• Internet connections - if you have problems connecting to the Internet, click on this item. At the next stage, the system will ask you to indicate what kind of problems arose: with access to the Internet in general or with connecting to a specific web page. In the first case, a test connection will be made to the website www.microsoft.com and if problems are detected, their description and recommendations for troubleshooting will appear on the screen. In the second, you need to specify the address of the problematic resource, and the system will find out the reason why it cannot be opened.

• Shared folders and Home group- these modes are used for diagnostics and troubleshooting network errors that arise when working with a connection to shared folders on other people's computers: the first - if access is carried out from a work computer, the second - if your PC is connected to home network. To detect the problem and view possible ways to resolve it, indicate the network location of the problematic folder.

• Network Adapter - Select this option and follow the on-screen instructions if problems are caused by problems with the network adapter. All actions are performed step by step, and, as a rule, the process of diagnosing and troubleshooting does not cause difficulties.

• Incoming connections - if you encounter difficulties with incoming connections (when the computer is inaccessible to other network participants), click on this item. Among other things, the Diagnostics and Troubleshooting Wizard will check to see if your firewall security settings are contributing to the problem.

Windows 10 network diagnostics

On Windows 10 you have new tool called "Network Troubleshooter". You can find it by clicking on the search icon in the bottom left corner and typing the word Network. In the search results, click on "Check Network Status" >> "Network Troubleshooter".

Another way to get to network diagnostics is to open Settings >> Network & Internet >> Network Troubleshooter.

Running the Network Problem Diagnostic begins the process of identifying your connection problems. After some time, this tool will show whether it was able to find any problems or not. When the problem is found, Windows Network Diagnostics will show a description and suggest a solution if possible.

Troubleshooting. To troubleshoot problems with your network adapter: the following actions:

To troubleshoot network adapter issues, follow these steps:

Check if there is communication using the Ping or PathPing command line utilities. Ping is used to identify network device problems and misconfigurations. And PathPing is for finding out whether packets are lost during multi-hop calls.

To display Ping statistics, use ping command-t. To display statistics and continue working, click CTRL keys+BREAK. To stop the operation, press CTRL + C. If lost packets are detected in the statistics, this indicates problems up to Communications Standard Layer 3 open systems(OSI) (IP layer communication).

If the connection to the remote system being accessed has big time delays (this applies, for example, to satellite link communication), you may have to wait longer for answers. The -w (wait) switch is used to specify more long time expectations.

Check the event logs for entries related to network cards or connections.

For more information, see the following Microsoft Knowledge Base article.

308427 View and manage logs Windows events XP using Event Viewer

Check if there is network adapter in the Microsoft Hardware Compatibility List.

Check other computers using the same default gateway that are connected to the same hub or switch. If they do not experience problems with network connections, the problem may be due to a faulty network adapter on your specific computer.

If this is the case, update your network adapter driver to latest version.

Contact the vendor of each motherboard and update the BIOS on the boards. Some network adapters and motherboards or BIOS version incompatible. Download the latest version from the vendor's website or contact your hardware vendor.

Check to see if the settings on the network adapter and the uplink hardware (hub or switch) match. Make sure that for all additional network resources(network adapter, hub and switch) are specified same parameters speed and duplex level. When the transmission mode is set to auto detect, auto detect, or automatic selection, make sure that automatic detection on all components is carried out correctly.

On some switches the task automatic detection for a full-duplex channel may result in the use of half-duplex. You may need to force full duplex.

Reset the switch, reboot the client computer, and test connectivity.

Switch the client and server to a passive hub. If communication resumes, the problem may be related to incorrect configuration network switch.

For getting additional information To set up devices, contact your equipment supplier.

Manually set the network adapter on the computer that is having connectivity issues to half duplex and a lower speed.

Connect the system to a switch that is configured for half-duplex and 10 Mbps speed, or use a 10 Mbps hub to ensure that a lower speed connection can be established.

To improve performance, manually increase the speed to 100 Mbps, and then restart your computers. Perform a loss test network connection, increase the value to full duplex, and then restart the computers. If network loss occurs, reduce the duplex level and speed, restoring the previous settings.

Replace network cable, connecting the failing system to a hub or switch.

Replace your network adapter with one that has been tested and proven to be reliable by following these steps:

Uninstall the network adapter diagnostic program.

Remove the network adapter in the network properties section.

Install a new network adapter.

Run Network Monitor on both ends at the same time network connection. After filtering the traces on the addresses of the two systems, compare both traces to see if the same traffic is shown.

Use TCP function Retransmit the Network Monitor Experts tool to detect TCP retransmissions by following the steps below.

Launch Network Monitor.

On the Tools menu, click Experts, and then click TCP Retransmit in the navigation bar.

Click Add to Runlist.

Click Launch Experts.

If frames are missing in one of the traces, check all intermediate cables, hubs, switches, and routers for hardware problems or configuration errors.

In Network Monitor, view the Capture Statistics frame. This frame is the last frame of the trace. If it contains a non-zero value in the following statistics counters, the communication error may be due to hardware failure or incorrect configuration:

STATS: MAC CRC Errors = 0 ( MAC errors CRC = 0)

STATS: MAC Frames Dropped due to HardWare Errors = 0

To ensure proper functioning, duplex parameters network switches and server network adapters must match each other. You must set full duplex or half duplex. Differences are unacceptable.

Computers on a local area network (LAN) typically share a full-duplex network environment. This configuration allows simultaneous data transfer by two computers.

Communication problems may occur if:

The computer has been moved to new port Ethernet switch that automatically detects network speed. However, the computer's network adapter is configured to force full-duplex communication at a static network data rate (10 Mbps, 100 Mbps, or 1 Gbps).

Both the switch's Ethernet port and the computer's network adapter are configured to force full-duplex communication at 100 Mbps or 1 Gbps. However Ethernet switch or the network adapter cannot communicate at this speed or use full duplex transmission.

The performance of an Ethernet-based LAN can be improved by using full-duplex equipment. This configuration allows two-way data exchange between network devices. Without full-duplex equipment, information is transmitted first in one direction and then in the opposite direction. In a half-duplex hardware configuration, packet collisions occur frequently, and each collision requires Resending package data. This results in increased traffic volume, which in turn contributes to decreased network performance.

When using full duplex, the receive and transmit channels are separated. Therefore, it is possible to simultaneously transmit and receive data without causing any collision. Due to increase bandwidth and collision-free, full-duplex link is more susceptible to cable termination failures or cable attenuation exceeding recommended limits. As a result, data may be retransmitted, which is enough to degrade performance.

The main task of diagnostics is to exclude the influence of third-party factors. Download to safe mode. If the problem is not observed in safe mode, it lies in third party service or program.

On this page:

Entering Safe Mode

In Windows 8 and later, go to Safe Mode it's correct to enter like this. The link describes login options from running system and recovery environments. I also raised this issue in the article Using the Recovery Environment in Windows 10 and 8.1, where I discussed different ways entrance to the environment and pictures with navigation through it.

There's a shorter way + R → msconfig → Boot, although it only works on a running system.

After reboot the computer will come in into safe mode. Please note, however, that to login normal mode you need to uncheck the box.

Service diagnostics

If there are no problems in Safe Mode, follow these steps: Win + R - msconfig - OK and go to the tab Services. Check the box Don't show Microsoft services.

Disable all displayed services (meaning only non-Microsoft ones) and reboot. If the problem does not appear, the problem is in one of these services.

Next, proceed using the “halving” method. Enable half of the services and reboot again. If the problem does not appear, the reason is the remaining disabled services. If the problem is reproducible, the reason is the enabled services - disable half of them and reboot again.

By doing this, you will be able to identify the service causing the problem and identify the program that owns it. Further, we can only recommend updating the program to the latest version or removing it.

Diagnostics of programs and drivers

You can do the same on the tab.

Note. In Windows 8 and newer controls startup is done in the task manager.

Here, too, you should not disable items manufactured by Microsoft. Disabling third-party software may cause devices to not function properly if you disable their drivers. Therefore, it is better not to disable the programs of your hardware manufacturers (for example, Intel), or to disable them as a last resort.

If these steps do not resolve the issue, follow Microsoft's recommendations for troubleshooting with a clean run from the Knowledge Base article