[plug] OT: hardware troubleshooting

[Andrew Cooks]

Hi Pluggers

I've got a problem with a box not powering up and I hope someone can help
me figure it out.

The box runs perfectly stable, even under load in the summer heat, but it's
always been 'temperamental' about powering up. When it has one of its
off-days (pun intended), I see the following:

When power is restored to the PSU, there are two clicks, about 100ms apart.
The first click starts the PSU fan, chassis fans and the leds signaling
motherboard power and ethernet power turns on. The second click turns off
the chassis fans and effectively stops the processor, but the leds and PSU
fan stay on. The system does not attempt to POST (no beep code, no bios
splash) and doesn't turn on when I close the power or reset pins.

So it seems like there's power on some rails, but not all of them.
Disconnecting/removing components from the system doesn't make any
difference.

I've had the PSU and motherboard and PSU+motherboard combination tested at
PLE in Wangara (where I bought the components), but the technician assured
me that everything works - the PSU, the motherboard with different PSU, as
well as the combination. Sigh.

Obviously it works some of the time, but today it doesn't.

The PSU is a Thortech Thunderbolt 850W and the motherboard is a Gigabyte
GA-X79-UD5.

How can I figure out what's wrong?

a.
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