Strange pre-post powerup problem

[brammers]

Hullo all

I'm trying to build a new PC using an ASROCK K7S8X motherboard with an XP 2800.

After plugging everything together, when you turn the PSU on at the back of the case the CPU fan spins for a little while, then shuts off. The power switch on the front of the case then doesn't do anything.

I've tried a different PSU that I know to work and that doesn't make any difference.

I've also tried reducing the PC to the bare essentials (CPU, RAM, gfx, HDD) and got the same result.

All ideas gratefully received!

[LWA]

Hey mate,
Is the cmos jumper in the correct place?
Sounds silly, but is the heatsink on the right way around?

[brammers]

Hi there.

The CPU and mobo were working fine in a previous chassis and haven't been changed since. They still look fine, haven't been knocked or anything.

The 2 pins for the CMOS jumper are clear, no cap across them. Is that right?

Thanks again

[LWA]

The CMOS jumper pins depends on the motherboard. For example, on my board there are three pins. Put the jumper on the top two means boot normally, the bottom two mean clear the cmos.

Just do a quick check in your motherboard manual to see whether you have all jumpers set in the correct place.

It is possible that your motherboard sets the fsb so if that is incorrectly set it could cause problems.

Thanks,
Leon

[brammers]

Ja, quick scan shows that it will boot normally unless the jumper is capped.

I'm a bit stumped with this one! Please keep going

[LWA]

Hmm running out of ideas

Did you check whether any other jumpers have to be set? Have you tried the ram in different slots, and just try one stick on its own? (that is if you have more than one stick of course).

Also check that no cables are shorting the computer that is a possibility.

[brammers]

Ok...

I've removed litereally everything from the board except for power switch connecter, PC speaker connecter and the power to the mobo from the PSU.

When I turn on the PSU it still spins its fan, before doing nothing else.

When it's not connected to the mobo it won't spin upon turnon. Turnon btw is from the switch on the back of the PSU, the case switch still does nothing.

Any ideas now?

[LWA]

Okay so you can't turn the computer on from the power switch on the case? The power switch lead can't be plugged into the correct pins, double check the motherboard manual to see where it should be in.

When you turn the psu switch on, the computer should not turn on... weird one..

[brammers]

Done some more fiddling.

The mobo is now out of the case. RAM, CPU installed.

Now turning the PSU switch on doesn't power up any fans.

Turning the case switch on does cause the CPU fan to whirr, but only for a few seconds.

We looking at a faulty mobo?

[LWA]

It does seem to be pointing to that fact, think you should wait for some more Hexus opions before you think about RMA'ing it though.

Sorry I couldn't be of more help,
Leon

[AaronTBE]

have you tried a different psu? if it doesnt turn on by the button and its DEFINETLY properly connected its a mobo problem

that is if the front case panel isnt knackered

[skuzgib]

Which PSU's have you tried - They're not Q-tec's are they?
I ask because I had exactly the same problem with a K7S8X and a Q-tec (this was before I new how bad they were). I thought it was the mobo, so RMA'd it, and the same still happened. When I swapped the PSU ( o a non Q-tec) it worked fine.