Computer turns on 5 seconds, shuts down

**macko** · January 25th, 2009, 01:20 PM

Six months ago, I built the computer. All had been working fine until yesterday. When I turn on the power the computer comes on for about 5 seconds then shuts off. After a couple of seconds, it tries on it's own to come on, but shuts off again. It repeats this on/off cycle. I noticed the CPU fan is not turning. There is only one place on the mobo to connect this 4 pin CPU fan. There is no display and no beep code. Need suggestions where to start.

System:
Gigabyte GA-P35-DS4 mobo
Intel Quad Core(Retail CPU/Heatsink)
2gb (1x2gb) Corsair Memory

**Steve R Jones** · January 25th, 2009, 01:23 PM

I would tyy new thermal compound for the cpu or a different psu.

**macko** · January 25th, 2009, 01:47 PM

I removed the cpu, cleaned the old paste and applied new paste. That did not work. While the CPU was out, I turned the computer on. It came on and ran fine. It did not shut down. I could hear the hard drive accessing. While the CPU was out, I plugged in the CPU fan. It did not turn. Does the CPU have to be in/working for the CPU fan to work? It looks like either CPU or mobo to me. Any other suggestions, comments?

**macko** · January 25th, 2009, 01:53 PM

I have a question. Even if the CPU fan does not work, why doesnt the computer come on? I would think it would take longer then a few seconds for the CPU to heat up. I would think you could at least get to a boot screen without the CPU fan going.

**stroyal** · January 25th, 2009, 02:59 PM

It's possible your BIOS looks for the RPMs on the fan, regardless of temp.

**stroyal** · January 25th, 2009, 03:10 PM

The laptop I am posting on had a similar problem last week, although it ran for 10 seconds before shutting down and restarting itself in an endless loop. That turned out to be a bad stick of memory.

**macko** · January 25th, 2009, 04:32 PM

Well, I replaced the fan, tried new memory, disconnected all devices, and replaced the power supply. Still no luck. So it would appear it is either the CPU or the motherboard. I don't have an extra CPU or mobo to try. I'll buy another CPU, can always use it if it turns out to be mobo.