PLEASE HELP! Computer turns on for 3 sec or so then turns off (repeating)

[justinstrack]

I have a computer which I just finished putting together and it turns on then powers off. It sucks because I have only on case I took everything out of it to put this new board and motherboard. I should of purchased another case guess.

So please help, why is it turning on for seconds and turning off?

*I'm going to go reset the CMOS to see if that helps, & take it off my UPS and see what it does also.*

*Tired resetting CMOS nothing, and plugging it in straight to the wall and still does it.

Please help.

[Alaron]

Double check all of the connections and make sure all of the power connections especially are in place.

Try our standard troubleshooter: PROBLEMS with a NEW BUILD? Try This!!

[justinstrack]

The problem turned out to be a "bad CPU"

I installed my original known-good CPU & it works, stayed powered up for a long time.

Have to get another CPU.

[Alaron]

CPUs do not go bad very often. It is possible that your heatsink was not properly applied, causing the chip to overheat and shut itself off. This would be very possible if you're using an Intel socket 775 heatsink. They are notoriously difficult to clamp down entirely. Might want to check that option. There are installation guides in the link I gave above.

[justinstrack]

Alaron

I did try to reseat it still same problem. As I might of posted before I had another known good CPU installed it and it worked fine. I assure you the heatsink had good contact with the cpu and it wasn't a heat issue.

It is going to back to Newegg today for a RMA replacement.

[glc]

It is also possible the CPU is not compatible with the motherboard - did you check compatibility before purchase?

[justinstrack]

Yes I did, it is a socket 775 Core 2 Duo 2.66ghz. I checked ASUS website with my motherboard P5B.

I installed a Quad-core processor using the same board and looking at the same specs on compatible CPU's on Asus's website.

[justinstrack]

This is an update to my processor problem. I received my new CPU this past friday and still the same problem. It powers on for a few seconds then turns off, repeating.

Yes, I am disappointed. But I noticed something after looking at the descriptions from my processors I have. My original process that I have for this board was a "65nm" and the processor I'm trying to replace it with is a "45nm".

I might of stated in an earlier reply that, I install my old processor and it work perfectly well that old processor was a "65nm".

Is that the root of the problem because I have a different, "nm."

I'm all out of ideas thanks for your input.

[Alaron]

Just to be sure, the Asus website shows that you need an updated BIOS to use most new CPUs with the P5B. I can't say exactly which because there are multiple chips that are "2.66Ghz Core 2 Duos". But have you double checked that the BIOS version you have is high enough?

It would help if we knew exactly which models of CPUs you are working with.

[justinstrack]

Thanks for your reply Alaron,

I know the BIOS has to be flashed but it doesn't give me a chance to do that. I have my old processor in it now and it is running fine, it is a 65nm.

Looking at tigerdirect's website on this motherboard, which is no longer availible it says 65nm, so I don't think it can handle a 45nm.

I never took that into consideration before now I will look closely at it.

Asus's website mentions 65nm on some processors but not all.

I know what I have to do now thanks.

[glc]

Sounds pretty easy - update your bios using the old processor that works.........................

It certainly can handle 45nm - but you have to look at the CPU compatibility chart on the Asus website carefully.