Computer suddenly won't start

[SirZach]

Hello, I built a computer 6 months ago and everything was working great, here are the specs:

4gb DDR3 Gskill Ram
Asus P7P55 LX motherboard
Intel core i5-750 cpu
Evga GTX 260 gpu
Corsair 650tx 650w psu

The problem that occurred the other day was that the computer just turned off by itself while I was using it and then starting turning on and off until I turned off the psu. When I tried to turn it back on it did the same thing: the lights would come on and the fans would start spinning for about 3-4 seconds then everything would turn off for 3-4 seconds then on again, it would then repeat this cycle until I flipped off the psu. Also during this cycle, the monitor would never receive any signal. My first guess was that this was a PSU issue, but when I replaced it with a known good PSU the same thing occurred. I have gone through the troubleshooting steps outlined in the sticky on these boards, but nothing seems to be working. I do not know what the most likely culprit of this problem would be and any help would be appreciated.

Thanks.

 

[Motopsychojdn]

I'd say go for a bread-boarding on it tbh, you've ruled out the psu, Go for one stick of ram, a Graphics card you know works and see how you go from there
Moto

 

[SirZach]

I tried it with one stick of RAM and a good gpu, but I still get the same thing. Could the mobo or cpu cause a problem like this?

Thanks.

 

[Motopsychojdn]

Quite possibly, although I'm afraid I'm now out of ideas myself,
hopefully another member will chip in and can help you out,
But Ill keep bumping the thread
Moto

 

[srynznfyra]

Motherboard sounds most likely. Replace the motherboard with a known good one compatible with all your devices and try again. I know how frustrating this sort of thing is especially when you don't know the cause of the problem.

Oh and you're sure there's nothing wrong with the BIOS settings? A flush of the CMOS wouldn't hurt (remove motherboard battery, put back in after 10 minutes or so).

 

[SirZach]

Okay, I replaced the motherboard and everything seems to be working correctly; the computer boots up and I can do my regular tasks. Only thing I have a question about is I am getting some beeps when I boot up and I am not sure what they mean, they are: beep....beepbeep....beep. Any ideas?

Thanks.