Bad motherboard or power supply?

[SlowLazyDog]

AMD Athlon 64 3200+ Venice
ASUS A8N5X
MSI NX7800GT
Thermaltake TR2 W0070 ATX 430W Power Supply
Seagate NL35 ST3250823NS 250GB

Everything was fine when I shut the machine off yesterday, but this morning it would power up but not give a dispaly nor give a post beep. I swapped out the video card and slapped in an old pci card and still no video signal.

The green light on the mainboard is lit up as is my CD-Rs light but none of the case lights are on. The hdd seems to spin, the vidcard, cpu and chipset fans are spinning but that's as far as I get.

Any ideas on what's wrong?

 

[doolittle]

If you have a voltmeter I would check the volts to see if they are all in spec, do you have a speaker connected to the mobo? If so you can try removing the GPU and / or memory you should get some beep codes if it detects the absence of mem/gpu. If not try removing all the connecting cables from the mobo save the speaker / power sw and clearing bios with the jumper & even removing the battery for a few mins.

To rule out the PSU you can jump-start it by removing the atx & 4-pin cpu connector (but leave the hdd / cdrom for +5 & +12 pull-up load) then short the ps_on connecter as such:

then you can check the unloaded volts then compare that to when it is connected to the mobo if there is a great difference could be the psu took a hit maybe there was a storm during the previous night?

 

[horstmann]

I bet your power supply. In my experience when a power supply blows, it takes other components with it.