Whats dead, M/B or CPU?

[martyg]

Hi all,

I'm attempting to resurrect an old Azza DVAX2+ motherboard to build a new system. Only piece I was missing was the cpu. The m/b is rated up to 800Mhz cpu's on an up to 133Mhz FSB.

Closest I found was a 900Mhz celeron, 100Mhz FSB.

Ok, so the problem is; board turns on, keyboard lights flash, video bios shows, board turns off (goes back into standby). Right at the point where the main system bios screen should come up. There's no beeping of any kind.

Result is the same if I pull out various bits like vid card, ram etc...then it'll just beep at me before turning off at the same point.

Any suggestions which piece is the dud? The CPU or the board?
Computer shop guys told me the cpu would just automatically scale itself down to whatever speed the board supports. Are they right?

Also, due to lack of a spare fan, the very first time I turned it on, I did so without one. Symptoms exactly the same (didn't get to system bios), board turns off after ~5seconds. Shop guys say this might have been due to processor overheating, and may have killed it. Do cpu's seriously fry within 5 seconds if they don't have a fan/heatsink on them?

Looking forward to any advice....coz I know the guys at the shop (where I bought the cpu) are just going to point the finger at me saying I killed it...)

-MG.

 

[Buz2b]

Do cpu's seriously fry within 5 seconds if they don't have a fan/heatsink on them?

AMD CPU's can but usually the Intel versions will not; instead they shut down. However, it is possible. Not to beat a dead horse but that was not a good move on your part.
As to whether it will "scale down", in some cases a compatible and supported CPU will do just that. However, this one may not be of the "generation" that is supported by your MB. You'll have to check the documentation to see for sure. If not there might be a BIOS flash that adds support.
It really doesn't sound like a bad CPU, simply because the darned thing begins the boot process. In most cases that means you have at least some funcionality in the cpu.
When you say "main system bios screen should come up", do you mean the point where the memory is checked and the IDE drives are listed? Or do you mean after this?
Have you tried resetting the CMOS? This might work.

 

[o1die]

Could be the fact that cpu heatsink fan wasn't plugged in. Some mobos will shutdown quickly without the cpu fan. Your mobo may not support the correct voltage for that particular cpu, and need a bios flash. Or you can use a socket adapter if needed with voltage adjustment pins.

 

[martyg]

Ok...turns out I can answer my own question.

Caution, user stupidity ahead....

I didn't have a spare ATX case to hand when I was building this thing, so for testing I hooked the PW switch connector on the M/B to the turbo switch on an AT case. (You can see where I'm going with this....)

ATX power switches are expected to be momentary, not stateful like the turbo switch was. By turning it on with that I was effectivly 'holding down the power button', which on this m/b forces it to turn off after 5 seconds.

Short term fix; hook it to the reset switch instead (which is momentary)
Proper fix; get a real case for it. (Might help the ports line up too.....yes....)

Cheers,
-MG.

 

[Buz2b]

Well, I have to give you credit martyg, at least you came back to admit your mistake. And don't worry, it won't be your last mistake when building computers; they happen all too often sometimes. Good luck on the rest of your project.