Need help finding the problem component: computer won't power up.

[brianb13]

We had a power outage about two nights ago and when it came back my computer turned on automatically. Except when it did the power supply started making a high pitched whine and it sounded like it was crackling. I quickly cut the power to the system and saw some smoke coming out of the top fan vent of my case (my PSU is mounted at the top of the case).

Assuming it was the PSU that fried I ordered a new one and hooked everything back up but when I hit the power nothing happens. The only thing I can see that let's me know the motherboard is receiving power is a little green light near the bottom of the board comes on.The light is labeled SB-PWR, which I'm guessing means southbridge? Other than that light there is no indication that the system is receiving power. Not even the new PSU is lighting up, here's the PSU I bought:
OCZ Fatality 550w
http://www.newegg.com/Product/Produc...82E16817341022

Anyway at this point I can't tell what the problem is. I don't see any blown transistors, none look browned on top, the CPU is completely clean and no pins are damaged or burnt. I don't know where to go from here and I'd hate to try replacing the motherboard since it would require basically a whole new system (see specs below). I have plans to buy a new PC relatively soon, but was hoping to salvage this one to pass down to my mother for a basic home computer. Any help is greatly appreciated!


System specs:
AMD Athlon 64 X2 4000+
Gigabyte AMD HD6850
2gig DDR2 ram
ASUS M2N-SLi Deluxe AM2 motherboard

 

[denis280]

HUM! With the smoke coming out of the psu.pretty sure you have more things fried. are you sure your psu is connected properly.

 

[brianb13]

Yeah everything is hooked up properly. I had an ancient gateway in the basement that I pulled out, dusted off, and hooked the new PSU up to and it worked fine. Guess my motherboard is fried as well, which means a whole new PC basically *sigh*. Call me lucky but after 15 years of building PC's I've never had a bad motherboard so I'm not used to diagnosing one. Was really hoping to hold off for Sandy Bridge to release before making a purchase but I need a PC for work.

One other somewhat related question: When I get a new motherboard and CPU (and probably RAM), am I going to have to format my harddrive? If so any tips on how to get my data off of it first? My Gateway is so old it doesn't have any sata ports so I can't use that to backup my drive.

 

[KGB]

Hold on there Brian...

Did you clear the CMOS? If not, clear it per your MB manual.

 

[brianb13]

I just tried to reset it KGB. I took out the battery, moved the jumper from the 1-2 position and placed it in the 2-3 position, waited about a minute then put it back to 1-2 and replaced the battery. There's still no response when I try to power up the system besides the green stand-by light.

What are the chances the CMOS battery is dead? The motherboard is about 6 years old.

 

[KGB]

I just tried to reset it KGB. I took out the battery, moved the jumper from the 1-2 position and placed it in the 2-3 position, waited about a minute then put it back to 1-2 and replaced the battery. There's still no response when I try to power up the system besides the green stand-by light.

What are the chances the CMOS battery is dead? The motherboard is about 6 years old.

Chances are good that it needs to be replaced.

For $2 it's worth the effort.