Pc Powers on for half a second then turns off

I'd recently been hit by a myriad of problems with my 2year old but well used system.

I used to have:
Gigabyte 78MLT-S2P
500W Xigmatek PSU
XFX 6770

I originally changed the PSU and GPU to CX750M and HD 7870 so that I had plenty of room to upgrade in the future and I put these in November due to PSU failing and wanting to increase my GPU anyway(I know the PSU failed for fact)

so these worked fine for about a month and it came to my attention that the PC would regularly crash when gaming but run fine in web browsing. I assumed that the motherboard was damaged when the PSU failed.

I have since upgraded my system to these parts:

Gigabyte 970A-DS3P(I know not great but good budget and I don't plan to OC)
Sapphire HD7870
Same 8GB RAM

Now yesterday I booted up the system fine and it was working all good(though the 8320 was at around 60degrees under load) I think it can operate at those temps? I'll be putting in a tx3 evo if not(to replace stock)

now after working fine for 8hours yesterday it will not boot this morning. Briefly the CPU fans/Case Fans and HDD all spinup (for a split second) then they power down.

Any help? thanks. I hope my CX750M isn't broken after a few months.
6 answers Last reply
More about powers half turns
  1. 1. Make sure everything is plugged in good and seated properly. A loose cable or circuit card can stop things from booting up.

    2. If I was a betting man, I'd say the power supply and/or motherboard are suspect. Power supply is more likely.

    Good luck!
  2. I really hope/don't think its my PSU since it's only 4months old. I did notice the ATX 24pin was loose so I ensured that was plugged in again properly. I've then checked my fan connectors/GPU

    I wonder if something is causing the PC to short circuit?
  3. You changed your mobo, right? Re-examine very closely where all the mobo supports are - those little (usually metal) posts mounted on the back of the case that the mobo fastens to at several holes. Ideally, there should be one support post under each of the holes in the mobo, and a screw through each hole into the support. MOST importantly, there must NEVER be any support post behind the mobo where there is NO hole in the mobo. Such a support post can contact a trace on the mobo back and short it to ground.
  4. I checked all of that Paperdoc when originally installing the motherboard and that wouldn't explain how yesterday it was working fine for 7hours. However I do have one piece of information. The VRM heatsink is a lighter colour on the ends...I'll post an image. I hope the VRM's aren't burnt out already? i've had the mobo 1month.

  5. You didn't mention if the system is making it past the POST. If you aren't getting a beep code from the MOBO, I'm going to stick with my first response. Powersupply and/or Motherboard is potentially shot.

    Being a new part just makes it that much more likely the cause. If a component is going to fail, it usually does so within a short period of time. I've had both PSU's and MOBOs fail after running fine for month or so. If you have a week component in the device, all it takes is a small power fluctuation to push it over the edge.
  6. I'll try rebuilding the system again and then I'll RMA the PSU/Mobo.
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