Troubleshooting a PC's PCU and motherboard

Problem : Friend of mine PC stop workin there was nothing coming on screen. So he asked me to help. I went check the pc , i thought sometihng mighe be wrong with Monitor or cables i check everthing and problem was not fixed. So i brought CPU home.

As my troubleshooting skills the next day I open box and try to boot pc but no bip sound i knw it's system board or powersupply one of them so i got dust blower and clean entire PC very nicely and than plugged in again .. woha this time PC reboots but keep restarting after few trials i was succefully able to reboot it and get in guest account i work twice.. but third time it simply didn't work same old problem. I suspect must be the power supply so i took out my computer power supply and hooked it up but didnt work. Nothin comes on monitor (monitor light yellow)

So i start takin out one card after other . clean everyhign make sure everying install properly , MEM , Processor etc etc, I checked CMOS bettery output its showing 3.somethin V it's fine i think. Now i have only few things connected to motherboard hardisk processor and Video card (only card for monitor) and try to reboot it but it doesnt work.. (the CPU and videocard fan works fine) i have spent couple hour on it... and i can't figure out. I m +ve that motherboard is not fried yet and it's look completly fine. Can anyone had experince with this type of problem suggest me . I check out put of power supply its lil less than 12v ithkn 11.59V but i guess that should be problem... I am thinkin to buy brand new power supply suggested by motherboard manugacture (GIGABYTE) and try to see if that solve problem. however I think it's something that shortcircuiting mother board. I have checked all caps and jumper on motherboard they looks fine. what should i do? any suggestion would be gr8 help.

Re: System board problem

What is the model of MoBo? I think that problem lies in motherboard...

I check out put of power supply its lil less than 12v ithkn 11.59V but i guess that should be problem...

Click to expand...

and what about 3.3V & 5V output from PSU?

Re: System board problem

PSU output are 3.3 and 5.3 V and 11.59V as i mention b4. well i have changed the powersupply with my workin PC and the results were same. The MoBO model # is GA -8PE800 Rev 1:1.

Re: System board problem

hallo,
if system goes hot befor cleaning, many components can be damaged, cpu, vga,...
for now do you hear the bip ?
on boot up, bios rutine recognise all components and at last the vga card,
if you dont hear short bep there are problem with your graphic card,
try to start without harddisk and another graphic card to becomme a black
window on monitor, afterthem set your bios to defaults, and try again,

System board problem

try to
1- run without CMOS Battery
2- remove the RAM complettly and monitor the beeb
3- try booting without HD , FDD , CDROM

to be sure about PSU check it with yor own PC
check the PSU U think it has fault on your own MB

reconnect the sockets of (PSW - Rst - spk - LEDs ) at there places
finally check the Micro Processor Fan and change the Heatsink Compounds y be dried