For the detectives out there..
We've had a classroom full (30) of Fujitsu Esprimo E3521 desktops for coming up to 2 years now (1 year of warranty left). For the first year they were mostly ok, from memory. Now there seems to be a problem with 5 or 6 that intermittanly won't boot in the mornings. We've resorted to checking this room every morning and swapping out (for another model) the ones that decide not to boot. When they don't boot, the power light comes on, the fans whirl up and stay on constantly with no output to the screen, and Fujitsu support haven't worked it out either. Two or three have been sent off and returned with no fault found. Here are the clues \ things I've tried:
It's not the motherboard or power supply, Fujitsu have swapped one or both at the same time on different PC's and the problem comes back.
It's not the cpu, heatsink or fan. Swapped one from a working PC when the fault occured, same fault.
It's not to do with the power source \ power leads. We've moved the PC's around within the room and the same ones are re-offending.
It's not the memory or any other connectable drive
I'm thinking it is something to do with a heat issue because the offending PC's if left unplugged from the power will work fine the next morning, but then ones that are turned off but are still plugged into the power can still pose a problem in the morning, and I can't see how these would be getting hot if they aren't actually on??
I'm going to try redoing the thermal paste when some arrives but wondered if anyone could throw anything else into the ring because I'm running out of ideas now.