I. Machine unresponsive, power light off, no power

1. Check power supply cable for proper connection.

2. Check all motherboard connectors for proper connection, such as the 6-pin connector and 20-pin power connector.

3. Check for any burnt components on the motherboard.

4. If there is a power indicator light on the motherboard, check if it is lit.

5. Trigger the power switch to see if the motherboard can start.

6. If none of the motherboard indicator lights are lit, short-circuit the green and black wires of the power supply to check if the power supply is working properly. Finally, replace the power supply to test if the motherboard is working properly.

II. Motherboard powers on but no memory POST beep

1. Check CPU power cable for proper connection.

2. Remove the northbridge and southbridge heatsinks and touch them to check for overheating, including the power chip, I/O chip, clock chip, etc.

3. Check all motherboard components. 1. Disconnect all peripherals, including expansion cards, VGA cables, KB cables, hard drive cables, leaving only the necessary power cables for the motherboard. Then, remove the memory and power on to see if the motherboard makes any beeping sounds. For chips like the 3680, use a buzzer for testing.

4. If removing the memory doesn't trigger any beeping sounds, clear the BIOS to see if the motherboard makes any beeping sounds.

5. Remove the CPU heatsink or fan and touch the CPU to check for warmth.

6. Reseat the motherboard.

7. Reseat the CPU.

8. Replace the CPU.

9. Gently press the Northbridge, CPU, and Southbridge.

III. The monitor doesn't respond after powering on, but there are memory POST beeps.

1. Check if the monitor's power and signal cables are properly connected.

2. Check for any loose components near the motherboard's graphics chip.

3. Enter the BIOS and press the Num Lock key. 

4. Check if the Lock light is on and off normally.

5. Clear the BIOS.

6. Touch the Northbridge to check for abnormal heat.

7. If there is a screen during POST and the system boots but no display, check if the computer is switched between screens. Press Ctrl+Alt+F1/F2/F3/F4, or press F8 during startup to enter Safe Mode or VGA mode to check if the motherboard displays normally.

IV. Computer cannot boot into the system.

1. Enter the BIOS to see if the hard drive is detected.

2. Check if the hard drive cable is properly connected.

3. Listen to see if the hard drive is spinning normally.

4. 1. Use MHDD to scan the hard drive for bad sectors.

5. Use DiskGenius to rewrite the Master Boot Record (MBR).

6. Check if the system is infected with a virus.

7. Reinstall the operating system.

8. Replace the hard drive and then reinstall the operating system.

V. Screen flickering during startup

1. Boot into Safe Mode by pressing F8 during startup to check if the problem is caused by incorrect driver installation.

2. Clean the gold contacts of the memory modules with an eraser.

3. Clean the memory slots with sandpaper. If you don't have sandpaper, try reseating the memory modules several times.

4. Replace the memory modules.

5. If the screen flickering persists after replacing the memory modules, the problem is likely with the motherboard. Replace the motherboard to test.