Here is a basic troubleshooting guide to use as an aid when debugging system problems. Be careful when following these guidelines as there are risks developed whenever a system is opened. If your computer is still under warranty, please read that warranty first.
Working on your computer by yourself can void your warranty.
This document is meant for people building their own systems, or with a computer out of warranty experiencing difficulties.
Won't Boot / Come Up. (No Beeps)
a) IDE Cable is plugged in backwards.
b) Memory is not correctly seated.
c) CPU is not correctly seated.
d) Video Card bad / not all the way down.
e) (If present) IDE/IO card not all the way down.
f) Motherboard has a grounding problem. (Remount/test on bench)
g) System oscillator is set too fast for the CPU. (Check settings and CPU)
Power supply fan does not spin + there is a humming noise
h) 1.44 floppy drive power cable is plugged in wrong.
I) Motherboard power leads are reversed/plugged in wrong.
j) (Non Pentiums) CPU is plugged in wrong.
k) System is not plugged in.
l) Monitor is not plugged into system.
m) Jumpers are not setup right.
Wont Boot/Come Up. (Beeps)
a) Memory bad/not seated correctly.
b) Video Card not plugged in all the way or bad.
Boots up partially - No ROM Basic error message / or asks for a boot disk
a) Hard drive is not partitioned or formatted.
b) C: partition is not set active.
c) C: drive is set up using the wrong parameters.
d) Hard drive does not have valid system files. (Sys C: after booting to a floppy.)
e) Hard drive data cable is bad or not plugged in all the way.
f) Hard drive is bad, and is unable to act as boot device. (Replace.)
System halts in boot process
g) Memory bad/not seated correctly.
h) External cache memory is bad.
I) Motherboard jumper switch settings are wrong.
j) BIOS/CMOS settings are wrong. (Load default set. [BIOS or Optimal])
k) System oscillator is set too fast for the CPU. (Check settings and CPU.)
HIMEM.SYS finds unreliable XMS memory.
a) Memory bad/not seated correctly.
b) External cache memory is bad.
c) System oscillator is set too fast for the CPU. (Check settings and CPU.)
d) (Older systems) BIOS/CMOS settings are wrong. (Load default set. [BIOS or Optimal])
General Protection Faults (GPF's) in Windows 95.
a) Bad or wrong memory. (Check for, or use tin lead EDO.)
b) Bad cache RAM or wrong cache RAM jumper settings.
c) Bad CPU.
System blows the circuit breaker when plugged in.
a) Leads from the power supply to the on/off switch are plugged in wrong.
Text mode characters wrong, or loosing pixels.
a) Video card bad, or not all the way down.
b) Bus conflict. (Move to a different slot.)
c) Motherboard is bad or jumpers are wrong.
Graphics/Windows problems.
a) Wrong or out of date drivers.
b) Memory on video card is bad. (Replace.)
Screen is shaking/out of sync
c) Vertical refresh rate is set too high. (Check drivers.)
d) Vertical refresh rate is set to an interlaced mode. (Try non-interlaced.)
Screen never shows a picture, but system boots.
a) Monitor is not on or plugged in correctly.
b) Video card may have gone bad.
Mouse doesn't work at all.
a) Drivers for the mouse are not installed or are the wrong ones.
b) Mouse isn't plugged in all the way.
c) Serial or PS/2 cable is not plugged in correctly.
d) Bus or PS/2 port card is not plugged in correctly.
e) Packing materials are still in, to protect the roller mechanism.
f) Mouse is bad.
Mouse doesn't work correctly.
a) Wrong mouse drivers installed.
b) Rollers are dirty, need to be cleaned.
c) Mouse is bad.
Modem not found.
Internal
a) Card isn't plugged in fully.
b) Com 2 on Motherboard/IO card isn't disabled.
c) Card jumpers not set correctly.
d) Modem is bad.
External
e) Modem is not on/plugged into a power outlet.
f) Modem is not plugged into a serial port fully on one or both ends.
g) Wrong serial cable (or bad one) needs to be a straight through, not a null modem.
h) Serial port cables are bad, wrong for Motherboard/IO card or not plugged in right.
I) Serial port is not enabled.
j) If an IO card is being used, card is not seated fully.
k) Serial port or modem is bad.
Modem won't dial out.
a) Cable to the wall is not plugged in correctly or is bad.
b) &C1 &D2 are not in the modem init string.
c) Interrupt conflict is occurring, Esp. with network cards.
d) Modem is bad.
Modem won't connect.
a) Interrupt conflict is occurring, Esp. with network cards.
b) Modem is located too close to a RF source. I.e.: video/hdd controller card. (Move one or both to a different slot.)
c) Bad phone line.
d) Modem is bad.
Floppy Drive problems.
a) Make sure there is only one controller.
b) Make sure the floppy is cabled and setup in CMOS correctly.
c) Check for a bad cable.
d) Check for a bad drive.
e) Check for a bad controller.
CD-ROM problems.
a) Make sure the right driver is loading.
b) Make sure the drive is cabled correctly.
c) Make sure the driver is looking for the right port/irq.
d) Check for a bad cable.
e) Check for a bad drive.
f) Check for a bad controller.
Hard Drive problems
a) Reconnect the splitter data cable.
b) Check that the drive is plugged in for power.
c) Check that you are using the right software.
d) Check for bad drive.
e) Check Master/Slave settings.
Only runs in DOS compatibility mode.
a) Check for viruses.
General Protection faults.
a) Bad CPU or Remarked CPU.
b) Bad/gold lead memory.
c) Bad external cache.
General crashes.
a) Run chkdsk /f for lost clusters.
b) ALWAYS Check for viruses.