Computer will not reliably boot (otherwise stable)

[crazystickfigur]

Hi all,

 

I have a computer that I built myself, I7 2600K, Gigabyte motherboard (can't remember the exact model off the top of my head), 16 gigs corsair vengance ram, corsair HX1000 PSU, 2x GTX 560TI.

 

My problem is the computer will not reliably boot (and it's not a software issue). When I try to turn it on, it will display the motherboard image for a few seconds just like normal and then power off for a few seconds, then power back on and it stays in this loop. In the meantime, I can't access BIOS nor can I actually view POST (gigabyte boards have that nice crappy welcome screen that you look at and have to press tab to view post, but I can't).

 

So it crashes and restarts before actually trying to boot.

 

Now if I turn it off, walk away for 20 min and come back, 7/10 times it will turn on and boot all the way through without issue. Now once the computer does boot, (to what ever device I want), it's fine, and boots all the way through and have never had it crash on me. It's stable, and I'll leave it on for weeks at a time.

 

Therefore in my diagnostic process:

I know it's not the HD (irrelavent because even with a faulty HD, I would be able to get into bios)

It's not the ram (ram that is unseated would cause a failed power on probably with a large beep, but the big thing is the computer would a: not power off, and b: never boot properly and not be 100% stable once booted)

Graphics cards also irrelevant.

House power irrelevant if again it is stable.

 

That leaves 3 options. The PSU, the Mobo, and the CPU.

I highly highly doubt its the CPU if my computer is 100% stable so I think it is either the PSU or the Mobo.

 

I find it hard to believe that the Mobo would cause this without having other problem. If it was the mobo, I feel like I would either never be able to boot or get crashes. Post doesn't change from one boot to another so I don't think it's the bios either. It either will pass post 100% of the time or never.

 

So that leaves the power supply. I've heard that computers are the hardest on their PSU when starting up, so that's the only logical explanation I have. It also explains why I never have issues once booted because I don't draw as much power. 560 TI's have a TPD of what? 160w? 2600K is like 95w. So at max load, it's still under half of rated capacity.

 

Any other thoughts / suggestions? I suppose I could try and borrow a friend's PSU and use that.

[crazystickfigur]

Update:

 

Almost certainly the power supply. Today while having problems booting, I flipped the switch on the PS while it was powering up (but before it failed booting) essentially making sure I fully drained the PS so I cut power while the comp was on. Plugging it back in, it powered up and booted first try. Coincidence, or is there something just glitchy with my PS?

[RAM GUY]

That may be the MB but You can use the link on the left and request an RMA and we can try and replace it.