PC boots up for less than a second then turns off

[Guest]

I've been having a problem with a PC i built about 6 months ago. It's a mid range gaming machine with an i7 920 and a X58A-UD3 Gigabyte motherboard.

Everything was going fine but i tried turning it on one morning and all the fans spin and it lights up put powers down after a second or less. I took it apart and put the motherboard on some cardboard with the powersupply and used a screwdriver to short the on switch. Exact same thing. Sometimes it will boot up for a couple of seconds or even longer but i get no output on the monitor. After it switches off if i then try to turn it back on it will turn off within less than a second.

I tested it out with another video card/RAM/power supply and the same thing happened so i presumed it was the motherboard. I sent the motherboard back to the manufactuer and i recieved it back today. I did a mock up on some cardboard again with just the power supply/RAM/CPU/GPU and the same thing happens as before. I tried unplugging the CPU fan, turning the computer on and then plugging the fan back in and it stayed on for a while but there was no monitor output. I tried doing it again and it just stays on for a few seconds before powering off so the same as before.

I'm pulling my hair out on this thing now, it's narrowed down to the cpu/motherboard but as both are less than 6 months old it's really annoying. I'm thinking of just taking them down to a computer store so they can tell me what i need to replace but i would rather get a forum opinion first because the money that i'll spending at the store could be spent on new parts.

 

[clarkjd]

Have you read this:

http://www.tomshardware.com/forum/261145-31-perform-steps-posting-boot-video-problems

and tried everything it lists?

 

[Guest]

I'm just worried they didn't actually fix it properly at the factory. I'll probably end up taking it to the computer shop where they'll have another i7 to test it with.

clarkjd: Yep done all those.

 

[T_T]

I am leaning toward a heat problem. Try scraping off all of the old thermal paste from both the CPU and the HSF. Using 95% -100% rubbing alcohol, clean the remaining paste from both components. If you don't already have it, go get some Artic Silver 5. Use the AS5 and apply lightly. Make sure that you spread it out evenly over the top of the CPU. Applying too much or too little can cause heat problems.

Second thing you need to be very certain of is the fan on the heatsink. If the fan has a short, it will not spin properly - in some instances, just one rotation. Should this be the problem, your CPU will overheat within seconds, causing the computer to shut down nearly instantly.

 

[Guest]

My post yesterday didn't seem to work.

I took it round a friends house who also has an i7 rig. His CPU in my setup boots up fine, with my CPU in his setup the fans spin and the motherboard lights come on but there's no output to the monitor. I'll return my CPU and get a after market heatsink. I haven't been overclocking it or anything but i think with the recent hot weather it may of caused it to go.

 

[Guest]

i believe i stated cpu earlier, glad you got to test it..
good-luck.

True, however i wasn't sure if they'd actually fixed the problem on the motherboard.