Hello,
I initially built this computer toward the later end of 2008 and it had been working soundly for sometime. Sometime around ~2012~, a friend had gifted me a MoBo+CPU -- so in time, I gradually UpGraded(*). Whilst I was using the alternate computer, I'd let someone else borrow the original PC ... for some unknown reason; they opened the Chassis and left it running for hours on end multiple times (unbeknownst to me). Sure enough, a fly landed in it and shorted the build. It was then returned to me shortly after the incident(*) and never compensated ... being that I liked the build too much; rather than taking the time soldering and repairing, I completely replaced the board (with almost an identical board) and confirmed everything functioning.
Sadly with everything going on at the time: I only initially re-built the rig (with an initial bench-test) then essentially put it into storage. *welp* The other PC a friend gave me became a devoted Living-Room terminal -- meaning I finally am making use of my 2008 computer again--which suffered some minor altercations...
• EVGA's 790i FTW (132-YW-E180-A1) ->replaced* to: EVGA's 790i Ultra SLI (132-CK-179-A1) paired with Intel's Qx9770 (+Zalman CNPS12X Cooler) @ ~4.0GHz w/ 16GB [4×4] @ 1866MHz RAM and a 600W "Ultra" (SLI-Ready) PSU
... I haven't considered replacing/upgrading the video-card any--as it currently is making use of 1× EVGA 1050Ti SSC and performing quite adequately.
*Problem*
- The computer boots and loads just fine, but then after a couple of minutes the whole system just Shuts-Down. ... Attempting to re-boot results in failure -- it demands to sit idle for at least 10-min minimum before it functions normal again. If I try to reboot right when it powers off, it just turns on for a second or so then powers off again.
Leaving it alone for sometime, I come back to boot it--but the BIOS resets?! ... implicating I have an "A:/" allocated/etc. ... This doesn't happen too often, only when I let it sit (unplugged) for too long [iSuspect*]
...
Help?


Thanks.

Yes.
Odd as it may sound,
I removed the charred-remains (of a Mosquito) myself.
Deducing it to be $easier$ to out-right replace the MoBo in its entirety--vs. repairing(*).
"Ultra" (ULT-XF600) X-Finity 600W PSU
...
I never considered it could be the PSU--since it turns on and such
***replace BIOS Battery -- *check*

Some of the reviews for that PSU are absolutely terrible.  I guess it was mediocre at the time comparing it to all of the other mediocre PSUs which existed back then, but compared to modern PSUs, looking back, it's worse than mediocre.  Replace it on principle alone.  Replacing it will probably fix that shut-off issue too.  Even if it was a good PSU, after so much time and degradation, it could easily be bad and out of spec by now.

Find out what was overheating?

Yep, you could do that.

I went ahead and removed my 790i from the Chassi, placed it atop a cutting-board with fan*, removed 100% everything with the exception of a VideoCard that requires no additional power adaptors, as well as a sATA-SSD and that's it--plugged it back up to the 600W Ultra X-Finity and have no idea what to do next...
In total, there are only 2× Optical Drives, 2× Auxiliary HDD's, a 3×chassisFans+4-pin PCI-Fan, a blueTooth/wiFi Card and Sound-Card + Primary sATA-SSD ...
It may sound hefty but I'm fairly confident 600W is ample -- based on the power-draw I may even be able to replace the video-card to a 2×GPU SLI format and it still might be sufficient enough a PSU (600W) ... in the meanwhile, I can't think of any way to "stress-test" my build,, but at the very least I'm going to let it idle for the time being to see what happens: before reassembling everything to its designated chassis.
*Boot Codes[?] - "C1" & "43" both hiccupped when initial bench-test .. but since then, everything seems nominal.
MoBo: LGA-775 EVGA N-Force 790i Ultra Sli (132-CK-179-A1)
CPU: 4-Core Intel Core 2 Extreme Qx9770 @ 3.74GHz + Zalman CNPS 12X
RAM: 16GB DDR3 [4x4] G.Skill Ripjaws X @ 1866MHz, CL: 9 (F3-14900CL8D-8GBXM)
GPU: 4GB EVGA GTX 1050 Ti SSC (04G-P4-6255-KR)
Chassis: Antec-900 Mid-ATX

Sounds like the motherboard... capacitors get old & start failing in weird, different ways.