[siwel16]

Basically whats in the thread title, when I turn the computer on it shuts itself of immediately after about two seconds, in this time the fans start up and the lights on the power switch go on, but that's the extent of it. Once it's turned itself off and the fans are nearly done spinning it'll try to reboot itself but then switch off immediately.

I've had my PSU checked and been told that it is working fine.

I've also taken all components out of the case and done a bench test, with the same result.

This has lead me to believe that it is a motherboard or CPU issue.

Was just hoping for some advice on how to identify which of the two has stopped working on me. and/or some suggestions for new gear.

Specs:
7970 Gigabyte vid card
g.skill 6g ddr3-1600
OCZ 700w psu
ASUS p6t se motherboard
i7 - 900 series processor

Without being able to access the computer this is all the details I can get on my specs.

 

[sevep]

Re: Computer turns on, only to turn off after 2 seconds

Hi,
What type of tests did you get carried out on your PSU?
Try swopping over your PSU with a known good unit.

 

[siwel16]

Re: Computer turns on, only to turn off after 2 seconds

Hi,
What type of tests did you get carried out on your PSU?
Try swopping over your PSU with a known good unit.

I went to Dcomp (a computer store) and they used a psu tester to test my unit. I don't actually have any spares as I've just moved to my grandparents place...

 

[sevep]

Re: Computer turns on, only to turn off after 2 seconds

Personally I would try swopping over the PSU with another unit (and even using a different power lead just to be sure) before delving any deeper as that test sounds quite basic and may not reveal a PSU problem under normal operating conditions if one did exist?

 

[siwel16]

Re: Computer turns on, only to turn off after 2 seconds

well hopefully i might be able to get my hands on a psu tomorrow and ill get back to you. I was dead sure on the psu being fine due to this test but i guess it's best to double check.

 

[sevep]

Re: Computer turns on, only to turn off after 2 seconds

Great, let us know how you get on.
Also try disconnecting some hardware from the motherboard and see if that makes any difference to the PSU "reset" time. That's a test you could do now which might show up a result and give us a clue?

 

[siwel16]

Re: Computer turns on, only to turn off after 2 seconds

I have tried this and it doesn't make a difference, also I will note that there are no beep codes from the motherboard, it's my understanding that the asus P6T SE has onboard sound?

I've even tried the bench test and nothing changes.

However something I haven't mentioned is if i hold in the power button it will stay on for a longer period as if it were starting up properly but after maybe 10 seconds it will shut down.

 

[sevep]

Re: Computer turns on, only to turn off after 2 seconds

Maybe the POST test has not had sufficient time to power up and launch, hence the lack of beeps?
See how you get on with another PSU and power lead.

 

[siwel16]

Re: Computer turns on, only to turn off after 2 seconds

ALRITE! so, I think I've fixed it.

I took the heat sink off the cpu, but left the fan connected to the motherboard, and the psu was also connected and from some miracle the computer stayed on.

I then turned it off quickly as not to burn out the processor, and applied the heat sink. Although it didn't work this time, I quickly tried the cpu without the heat sink and again it worked.

I then inadvertently applied the heat sink rotated a different way and the computer turned on again with heat sink intact.

Since then I've applied ram and the GPU and still the computer continues to turn on and stay on, I've even reached the BIOS on the monitor.

I believe this to potentially be an over heating issue, where the thermal compound has worn down in bits and by rotating the heat sink, I've temporarily fixed it. So to fix this permanently I just need to re-apply some thermal compound.

Does this make sense or have I just struck gold and hope the computer keeps working?

I will now proceed to put the motherboard back into the case and reconnect everything and report back.

 

[Tyree]

Re: Computer turns on, only to turn off after 2 seconds

The old needs to be thoroughly cleaned from the heatsink & CPU and to be reapplied since you removed the heatsink from the PSU. Do that before doing anything else.

Testing a PSU with a PSU tester only confirms the PSU is putting out power but does not determine if the PSU has sufficient power to boot the PC.
OCZ PSU's are not the best quality but yours should be sufficient. What is the Model Number and age of your OCZ?
If you did a proper bench test, precisely as listed below and no change, refer to the last paragraph.

Remove EVERYTHING from the case.
Set the motherboard on a non conductive surface. The motherboard box is perfect for this. DO NOT PLACE THE MOTHERBOARD ON THE STATIC BAG! It can actually conduct electricity!
Install the CPU and heat sink.
Install 1 stick of RAM.
Install the video card and attach the power supply connection(s) to the card if your card needs it.
Connect the monitor to the video card.
Connect the power supply to the motherboard with both the 24pin main ATX Power connection and the separate 4 pin (Dual Core CPU) or 8 pin (Quad Core CPU) power connection.
Connect power to the power supply.
Do NOT connect ANYTHING else. Make sure you have the power connector on the CPU fan connected.
Use a small screwdriver to momentarily short the power switch connector on the motherboard. Consult your motherboard manual to find which two pins connect to your case's power switch. Then touch both pins with a screwdriver to complete the circuit and boot the system.

If all is well, it should power up and you should get a display. Then assemble the parts into the case and try again. If the system now fails to boot, you have a short in the case and need to recheck your motherboard standoffs.

If the system does not boot after this process, then you most likely have a faulty component. You'll need to swap parts, start with the power supply, until you determine what is defective.

 

[siwel16]

Re: Computer turns on, only to turn off after 2 seconds

Everything is working exactly as expected now, which would lead me to assume it was definitely the thermal compound and not the power supply.

I did indeed do the bench test, and everything seemed to work and then i reloacted the motherboard into the case.

Glad to be done with that!

Thanks for the help guys.

 

[Tyree]

Re: Computer turns on, only to turn off after 2 seconds

Glad you got it resolved and thanks for posting back with the fix.