Hardware Reference
In-Depth Information
In fact, just about any intermittent system problem can be caused by the power supply. I
always suspect the supply when flaky system operation is a symptom. Of course, the fol-
lowing fairly obvious symptoms point right to the power supply as a possible cause:
• System that is completely dead (no fan, no cursor)
• Smoke
• Blown circuit breakers
If you suspect a power supply problem, some of the simple measurements and the more
sophisticated tests outlined in this section can help you determine whether the power sup-
ply is at fault. Because these measurements might not detect some intermittent failures,
you might have to use a spare power supply for a long-term evaluation. If the symptoms
and problems disappear when a known-good spare unit is installed, you have found the
source of your problem.
Following is a simple flowchart to help you zero in on common power supply-related
problems:
1. ChecktheACpowerinput.Makesurethecordisfirmlyseated inthewallsocketand
in the power supply socket. Try a different cord.
2. Check the DC power connections. Make sure the motherboard and disk drive power
connectors are firmly seated and making good contact. Check for loose screws.
3. Check the DC power output. Use a digital multimeter to check for proper voltages. If
it's below spec, replace the power supply.
4. Check the installed peripherals. Remove all boards and drives and retest the system.
If it works, add items back in one at a time until the system fails again. The last item
added before the failure returns is likely defective.
Manytypesofsymptomscanindicateproblemswiththepowersupply.Becausethepower
supplyliterallypowerseverythingelseinthesystem,everythingfromdiskdriveproblems
to memory problems to motherboard problems can often be traced back to the power sup-
ply as the root cause.
Overloaded Power Supplies
Aweakorinadequatepowersupplycanputadamperonyourideasforsystemexpansion.
Some systems are designed with beefy power supplies, as if to anticipate a great deal of
system add-ons and expansion components. Most desktop or tower systems are built in
this manner. Some systems have inadequate power supplies from the start, however, and
can't adequately service the power-hungry options you might want to add.
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