Installed new CPU+GPU - fans spin up for 3 seconds than nothing.

[CuriousMike]

Tonight I purchased a new
Intel 4590 (Frys special)
nvidia 950
ThermalTake tower fan while doing the upgrade.
The CPU/GPU are replacing a G3220 and a 7770.

The machine initially powered on (Windows 7). I was in the middle of having Windows 7 create a media usb drive for Windows 10 when the machine powered off by itself.

When attempting to power it back on, the CPU and GPU fans spin up for 2-3 seconds, than nothing.

I removed everything, piece by piece to see if I could narrow down the culprit.

At this point, I'm down to just the CPU + HSF, motherboard sitting outside of case. (No videocard, no memory, no HDD... nothing. Just CPU + HSF and the power switch + two power cords (main board power cable and CPU power cable.)
Again, in this config, CPU fan spins for a second than nothing.

Any ideas what might have gone bad?
I'm assuming at this point that the new GPU is still OK, and I either
a) Fried the motherboard
b) Fried the CPU

 

[CuriousMike]

New discovery - I figured I'd take the HSF off, assuming the worst.
The TT HSF tower uses two screws to tighten the assembly down - when I had the screws ... maybe half loose? ... on a whim (thinking maybe something was shorting around this install) -- I turned it on and the CPU fan stays on.

Maybe I'm over-tightening the CPU HSF assembly? I'm going to continue on this investigation...

 

[CuriousMike]

I took apart the HSF, and rotated the rear plate 90'... re-assembled, and it's running again.

The back plate isn't a simple rectangle ( suppose they can't be ... needing to support various sockets.) -- maybe it's my mobo - but the backplate can just weirdly rub a few pins that I suspect 99% of other boards it won't rub. Yes, it has a foam backing -- but when screwing it down, the foam compresses and maybe a short was happening.

Anyhow, it's tenuously solved for now.

 

[VirtualLarry]

Good job figuring that out.

I just built an ITX PC, with an "Apevia ITX 200" case, and it was a tight fit. Too tight, I had to tighten the DVD drive down on top of the Intel retail HSF assembly, such that it might crack.

 

[CuriousMike]

I presume all these PC manufacturers have "standards" that dictate distances and measurements -- some of them I think have a looser following of those standards.

Hence you have HSF smashing into ram-sticks or HSF back brackets shorting out memory pins or DVD slammed into a HSF.

Ugh.