No Video No Beeps?!?!

[HouseOfTechs]

i have a cust built ausu p4p800 motherboard here....
Cust brought it in.. power supply was burnt.smelled it as soon as she walked in..
replaced it.. working great then i get a call 1 week later that shes getting no video but it did work when she brought it home...


Have the machine on my bench thinking is a bad motherboard. No Video No Beeps?!?! The monitor is responding to something because the screen changes to just a black screen when vga is plugged in.


I tried different ram, power supply, vga card, unhooking all cable except the motherboard 4 pin and 20 pin,
reseated cpu fan and north-bridge heat sink...

One thing i did notice is the northbringe Heatsink is HOTTTTT!!!

anything i miss? bad motherboard??

 

[Ccomp5950]

Sometimes HP desktops do this and I reset the cmos, yank the battery or use the dipp switch to clear it.

When the power button is pushed do the fans come on?

You can check for shorts with a multimeter. Black is ground, if any of the other colored cables show continuity with black that's a bad motherboard.

In these pictures I'm using the case as "Ground"

Ground to ground (showing full continuity, this is expected):

And 12v to ground (Showing very little continuity, this is expected as well):

 

[HouseOfTechs]

k forgot to mention i did clear cmos also
Fans do come on on the vid card and also cpu fan
will check for shorts now.. where would they occur? in the 20 pin connector?

 

[Ccomp5950]

http://www.smpspowersupply.com/connectors-pinouts.htm

I don't believe you have to check every pin, just one of each 12+ 12- 3.3+ 5+, I'm not absolutely sure of that though.

 

[HouseOfTechs]

k i get continuity with orange cable slot for a brief second.i guess that would mean there is a short and its a bad motherboard correct?.. black cable slots shows continuity constant.

 

[Encrypted Existence]

black cable slots shows continuity constant.

It's supposed to. Black=ground

 

[Encrypted Existence]

http://www.smpspowersupply.com/connectors-pinouts.htm

I don't believe you have to check every pin, just one of each 12+ 12- 3.3+ 5+, I'm not absolutely sure of that though.

Got a 404 when I clicked on your link. Good info in the post with the pics though. Thanks.

 

[HouseOfTechs]

It's supposed to. Black=ground

yea i was just putting it out there

 

[Ccomp5950]

html not htm, my fault.

http://www.smpspowersupply.com/connectors-pinouts.html

 

[Ccomp5950]

k i get continuity with orange cable slot for a brief second.i guess that would mean there is a short and its a bad motherboard correct?.. black cable slots shows continuity constant.

No, if it was shorted it would be constant.

 

[HouseOfTechs]

hmmm out of ideas.. might be motherboard

 

[Ccomp5950]

That is the direction I would be leaning now, you can't say conclusively that it is the problem but that's what it appears to be.