I have a Dell Optiplex GX280 that's restarting randomly. I've checked everything I can think to check, and still can't find the cause. The user describes the restart (which, unfortunately, I have yet to be present for) as: "A quick, high whine, and then it turns off." I've tested the mobo, proc, memory, HDD, and power supply. I've checked the fans. I've checked for blown caps. I've reseated all connections. I've even replaced the CMOS battery and PSU with known good/working ones.
I don't think it's going to be anything related to software, since the user has indicated it doesn't seem to shut down on her while she's doing any particular thing. The high-pitched whine she describes should also be a good indicator that I'm looking at a hardware problem, I should think.
My first thought was PSU or possibly fan failure/overheating, but neither appear to be the case. Any ideas?
Any advice at this point will be greatly appreciated.