Archive for March 2nd, 2010
Basic Computer Troubleshooting
Symptoms are presented in the order of boot progression. This does not attempt to explain every issue, simply the most common ones that prevent the operating system from starting normally.
No response to the power button (no power light, no spinning up of fans, hard drives, etc) indicate one of the following issues:
- System is not getting good power
- Check the power cables and internal connections
- Verify the power supply is sending good power using a reliable tester
- System is not responding to power
- Hardware has a problem and must be repaired/replaced. Typically the fault is in the motherboard and/or power supply and/or related cables/connectors.
- This could also occur if one or more ports or devices (typically USB) are damaged/broken or a short-to-ground condition exists.
- System has a short-to-ground or open-circuit condition
- Visually inspect the system for liquid damage and/or corrosion.
- Try bench-testing the system. (Remove the motherboard from the case and build it on a non-conductive surface to see if the board is shorting to the case).
- Check USB ports for damage.
- Remove all components from the motherboard (including the CPU/heatsink) and test.
IMPORTANT: If the CPU is part of the board (soldered-on) leave the heatsink mounted to the board. Damage to the CPU may result if a heatsink is not attached. If the system responds to power, replace components one-by-one and retest to find the fault.
Power light comes on, fans and hard drives may or may not spin up, but there is no other activity. Floppy drives (if present) usually do not do a seek test, no video output is displayed, and the system is otherwise unresponsive.
- Check internal cabling. If the cabling is correct, the most likely cause is a hardware issue with one or more of the motherboard, power supply, memory, or the CPU.
Loss of power after 1-4 seconds or system reboots within 1-2 seconds of powering on
Power button may go off and then back on, fans may cycle, POST screen may appear over and over (but does not finish), etc. If the POST completes, see Incomplete POST below.
- See ‘no power’ above. This certainly indicates faulty hardware.
Similiar to “no POST”, except the OEM logo appears on the screen with a progress bar, but it does not progress after a reasonable amount of time.
- The most likely cause of incomplete POST issues are: bad motherboard, memory, or processor.
The system powers on, the OEM logo appears and progresses to a blank screen in preperation to boot the OS, however, nothing happens. The OS logo does not appear and the screen may remain black with a simple flashing cursor. Or, the system may reboot.
- Likely causes are: bad hard drive (or cable), corruption of the operating system, or in less frequent cases, bad memory, motherboard, or processor.
Somewhat trickier to tell apart from no post, but with a much narrower scope of possible problems. Similiar to no post, the system powers on but there is no BIOS logo on the screen. Unlike no post, drives perform their self-tests and there is hard drive activity (indicated by the HD activity light) and you may hear startup/login sounds.
- Check the display (monitor) is powered on. Check to make sure cables are connected correctly and the monitor is set to the correct input source (if applicable). If all else fails, the motherboard, video card, and/or the monitor may need to be replaced.
System shuts down after a period of time
System shutting down usually indicates one of the following:
- System is overheating / “thermal event”.
- Check and clean heatsinks
- Reapply thermal paste
- Check fan operation; replace as necessary
- Power supply is failing under load
- Replace power supply
- Some other hardware component is failing under load
- Test/replace memory, motherboard, processor.