Hardware Reference
In-Depth Information
By using S3 Sleep mode, you can effectively leave the system running all the time yet still achieve
nearly the same savings as if you turned it off completely. Servers, of course, should be left on
continuously; however, if you set the system to Wake on LAN (WOL) in both the BIOS Setup and in
Windows, the system can automatically wake up anytime it is being accessed. The bottom line is that
taking advantage of Sleep mode can save a significant amount of energy (and money) over time.
Power Supply Troubleshooting
Troubleshooting the power supply basically means isolating the supply as the cause of problems
within a system and, if necessary, replacing it.
Caution
It is rarely recommended that an inexperienced user open a power supply to make repairs
because of the dangerous high voltages present. Even when unplugged, power supplies can
retain dangerous voltage and must be discharged (like a monitor) before service. Such internal
repairs are beyond the scope of this topic and are specifically not recommended unless the
technician knows what she is doing.
Many symptoms lead me to suspect that the power supply in a system is failing. This can sometimes
be difficult for an inexperienced technician to see because at times little connection seems to exist
between the symptom and the cause: the power supply.
For example, in many cases a parity check error message can indicate a problem with the power
supply. This might seem strange because the parity check message specifically refers to memory that
has failed. The connection is that the power supply powers the memory, and memory with inadequate
power fails.
It takes some experience to know when this type of failure is power related and not caused by the
memory. One clue is the repeatability of the problem. If the parity check message (or other problem)
appears frequently and identifies the same memory location each time, I would suspect that defective
memory is the problem. However, if the problem seems random, or if the memory location the error
message cites as having failed seems random, I would suspect improper power as the culprit. The
following is a list of PC problems that often are related to the power supply:
• Any power-on or system startup failures or lockups
• Spontaneous rebooting or intermittent lockups during normal operation
• Intermittent parity check or other memory-type errors
• Hard disk and fan simultaneously failing to spin (no +12V)
• Overheating due to fan failure
• Small brownouts that cause the system to reset
• Electric shocks felt on the system case or connectors
• Slight static discharges that disrupt system operation
• Erratic recognition of bus-powered USB peripherals
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 following fairly obvious
 
 
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