Random Shutoffs (Most of the time before Windows)

Sorry if there is a thread on this (I found many but most were not exactly what I have). Also, if this is in the wrong thread I apologize (first ever post here)

So I'm trying to fix a computer for a friend. All the parts seem fairly recent and new, all the fans are running and nothing seems to be overheating. But the computer randomly switches off (not to be confused with rebooting). They seem to be random, sometimes it will get past the win loading screen and switch off mid load, other times it gets no further then the mobo screen. Most of the time though, it wont even get to the windows loading screen before it switches off. A lot of the time it just freezes on the Mobo screen and the keyboard does not respond (no bios entrance then) and switches off moments later. I did get it to boot the first time and ran a HWmonitor and none of the temps stood out. That one time i got it to boot, it was fine for a bit, then it got a bluescreen and then switched off mid bluescreen "scan". The POST does beep once while it is booting which is confusing because doesn't that mean the mobo is a-ok?

Any help would be appreciated, I figure its either a problem with the power supply or the mobo itself.
Thanks in advance
-Ryan

 

Greetings, Blueman101.

What's the make and model # of the machine? What operating system and service pack #? Any information you can provide will be helpful.

First things I'd suggest would be:

Visually inspect all hardware for obvious signs of damage.
Check all connections (power and data).
Reseat the RAM module(s) - if using multiples, try swapping and/or using one module at a time.
Disconnect/remove all non-essentials (sound card, modem, etc.), see if the symptoms change.
If available, use onboard video in lieu of a graphics card for troubleshooting.
If possible, get into the mobo's BIOS and reset everything to safe defaults.
Try reseating the processor, checking for any bent or broken pins.

We would have to know the motherboard/BIOS version in order to decipher the meaning of the single POST beep.

 

You say fairly new - did it ever work right?

I would start by swapping in a known good power supply. If that holds, then looks at RAM, perhaps one stick at a time.

Fortunately, Intel CPUs don't have pins anymore. I wish AMD would follow suit. But nevertheless, I would think if a CPU connection was damaged, you would have consistent problems but you say you are able to complete boot sometimes. Since that is the case, and handling the CPU is so risky, I would save that check until last. However, I would want to verify a proper layer of TIM (thermal interface material) was used so you might want to inquire able that.