hardware failure troubleshoot
 

hoping someone has some ideas.

I have 2 computers at home plugged in, but powered down. i return after a day away from the house. i turn them both on, one fails to boot at all, but 'comes on' with fans, etc. never displays anything on the screen. power light is on and HDD indicator is on. Hums and hums, no beeps, just nothing.

The other pc actually booted up normally, but after 15 minutes, screen flickered and it crashes. It will not boot anymore. It reaches a point where the bios screen says it has detected a hardware fault, invalid cpu speed setting. then it shuts down. If i wait awhile, let it rest, sometimes it reaches grub, but it always crashes. Almost like a very fast overheat.

both were solid machines when i left them only a day before. very little chance they were tampered with.

An old, old machine which wasn't plugged in powers up normally, runs fine. So does a laptop. Routers, switches, etc., all fine.

No indication of a power failure while i was gone.

My thoughts are:

1. power surge
2. lightening strike
3. ???

Anyone have ideas about this? Especially - how to troubleshoot; assuming a massive power surge would it be memory chips or cpu fried.?

Please, advice appreciated.
danimalz

Any electrical overstress condition (ESD, EMI, RFI, EFI, etc.) that found its way to the motherboard could have fried any and everything. There's really nothing more susceptible than another in modern electronics.

However, you said that the machines were shutdown while you were gone. A power surge likely wouldn't have found its way through the power supply in this situation. In fact, the power supplies in PCs are designed to tolerate lines power surges/sags and maintain a regulated output. Obviously, there's limits to the magnitude of surge/sag. But, if the surge/sag exceeds some value, the power supply is probably designed to shut itself down. Any perturbation to the grid significant enough to cause surges and sags would have probably been the result of something newsworthy. Even if Diablo Canyon or San Onfre tripped off-line you probably wouldn't know it.

Now, that's not to say that the power supplies aren't toast. And it really wouldn't be that odd to have both fail at the same time. It also wouldn't be that odd to have them fail on power up. One of the worse things you can do for electronics is turn them on and off. The lights for power and the HDD are pretty robust devices that will tolerate a lot of garbage from their power source. The really important stuff like the motherboard components definitely will not. If it is your power supply and you haven't toasted anything, don't keep turning the PCs on. Eliminate the power supplies as the source of your problems.

Is the BIOS still correct in the second PC? With the machine turned off, you are relying on the battery to maintain the BIOS settings. If the battery is weak, your BIOS can corrupt.