Random Computer Reboots!

[Sora]

Funny thing, i had pages and pages of what i have done and i realized i was on that computer and then it shutdown on me. Think my neighbors could even hear me swearing. haha!

Anyways i'll make this descriptive and brief

I am trying to fix a computer for someone, it is a custom build. It will randomly shut down at any given time. Could be a few days to a few seconds. and then keep staying on less and less before each shut down until it is just... on, off, on, off...

i surfed the web and checked a few ideas out and this is what i've done so far.

Checked to see if the bay doors were covered with dust; All clean
Replaced the liquid cooling unit from the CPU and placed in an old INTEL heatsink i had, still happened.
Checked for bad memory modules, although he didn't have one in all the way and was reading 8GB i came to the conclusion that it was faulty memory, correctly inserted it; POST said 12gb ram.. huzah! 2 minutes later shutdown...
checked for software issues and couldn't find any extent; although i have been wrong before!
checked to see if the graphic card was working correctly, it was and even checked inside to see if there was dust built up in the fan... It was all clear.

Although there is something that has driven my suspicion... The power supply, when it is plugged in, moving the chord will cause it to either turn off or stay on longer as its going through its on, off, on, off, fits... also i could swear i might here a wee bit of a hiss or snap when i do that... Debating if this is one of those rare power supply cases cause i dont feel like having to buy a new 800W power supply. lol

Thank you for your time,

-Sora

[Sora]

UPDATED: just tooke the heatsink off, checked for thermal pasted and reajusted, noticed that the mobo is not lined up with the sink grid behind it causing incorrect seating, maybe it was overheating???
will keep posted and please feel free to suggest ideas.


Edit: Lasted about 5 minutes, back to doing the same thing.

[Sora]

Update : Replaced the power supply with a GS800 problem seems to be gone, will keep updated.