computer crapped out, now will only 'pulse' when i try to turn it on

ok here is a breakdown of my computer ...

Ultra 512MB PC3200 DDR 400MHz CL3 (2 of em)
AMD Athlon 64 4200+ Socket 939 (Manchester)
Gigabyte K8N Pro-SLI Socket 939 Motherboard
XFX GeForce 6600 128MB PCIe Extreme Gamer Ed. (2 of em)
Antec 550w PS

the computer has ran great since oct when i built it ... but today suddenly while playing a game it shut off completly. when i tried to power it back on it would not come on ... i turned the main switch on the PS off and back on and the fan's in the case and PS would pulse .. (turn on for a second then back off) but nothing else would turn on ...

i tried a different power supply in the computer and it does the same thing, tried this ps in another computer and it works fine ..

what else could be causing this ??

I was going to say that this is usually casued by a bad power supply but you ruled that out already.

Look at your Mainboard for buldging or leaking capacitors. I'll bet your Mainboard is toast.

Welcome to the forums.

It does sound like dead caps. Did you hear anything from inside the case (pop, etc) when it shut off the first time?

hmm i will take another good look at it and prob pull it on out ... from inside the case with wires and such moved out of the way i don't notice any of the caps being bad (leaking, or buldged) but it may just be a small one that is hidden by something else ...

as for a sound ... well the volume for the game was up pretty good there was a faint thump type sound when it shut off but i figured that was just the HDD and fan's stopping suddenly ... might have been a cap blowing tho ...

and thanks for the welcome, i have read the forums for a few years only just now posting because i am stumped with this problem and couldn't find an answer with search lol....

I had the exact same problem pffft. It was blown caps on the mobo

This has happened to me with the same exact symptoms and no blown caps. I did some testing on another
mobo and cpu, turns out my motherboard died. But the worst part about it was the cpu was fried too.

I actually had the exact same "pulsing" problem today with my computer at work and it ended up being a bad PSU. Wish I could be more help but my problem was fixed with a new PSU.

Bad part is, it can be any number of things, none of which are cheap. Do you have access to anyone that uses a similar setup that would allow you to test components?

sadly, i dont have access to anyone with a similar system. and my other comp's at the house dont have SATA or PCI express ... or the processor style ... only thing i can try out in another comp is the memory ... which i will do later this evening when i am taking it apart to check out the motherboard and processor better ... if i can't find anything that looks like it might be bad i will take some pics to share to see if others might notice something that i didn't

Make sure the 4-pin connector is tightly fit to the motherboard, the same symptons (pulse) can show up if you don't have this connector working correctly.

its the motherboard you might of fryed it or static did something

here is a side question...what would cause a cap to bust? i had that once and it really sucked because i didn't konw it and it leaked all over my stuff sad

That happens when the "barrier" between the positive and negative plates within the cap breaks down (I can try to find a diagram somewhere). That can be caused by age or just a bad batch from the factory.

i had a very similar problem with my old socket A soltek motherboard. it quit working one day and i couldn't turn it back on for about 30 minutes.

i figured the problem was due to bulging (and a few leaking) scandilous caps around the cpu socket, they said GSC on them - high quality stuff

okay i have stripped the computer down and inspected each part .. i find 0 signs of bad caps or the usual overheating signs ... all the caps have a good uniform size and the tops are flat with no bulge to them at all .. no signs of leaking at all on the motherboard ...

double checked over the vid cards and same thing .. processor looks good to, but its hard to tell just from looking at them ... but the paste was still plyable and covered it evenly ...

all the fans worked before it shut down .. so i still have no clue ...

the company i bought it from (tigerdirect) won't RMA it for me .. because i do not have all of the origonal packaging (i have the static bag, software, accessories .. but no box) so looks like i have to go to gigabyte for it ... they have like a 4 to 6 week turn around tho =( ... i just wish i could know for sure what it is before i get parts sent off ...

is there any way to check the motherboard better? ... or the processor? ... i dont have access to a similar computer to swap parts in ... i have checked the memory out, it is fine .. its in the computer that i am using right now ... but the vid cards are PCIe and none of my other comps have that .. same with the 939 socket ...

i have a pic of it but it is 1.3meg in size and i can't upload it ... (other comp has photoshop on it, not enough free space on this one to install many programs) ...

well i still haven't had any luck getting an RMA for the board ... but i did narrow it down to just the board .. found someone that i could test my vid cards and processor ...

i have gone ahead and ordered a different board while i deal with getting this one RMA'd ... not getting gigabyte anymore .. this will be the second board i have had of theirs that has crapped out on me ... (with no overclocking at all)

BIOSTAR TForce4SLI is what i have ordered .. seems to have some good reviews and promising info from others that are using it right now.... much better then the ones of the board i did have.

It's the mobo. Gigabyte = CRAP. They use **** caps and their boards are gargabe otherwise.

Edit: you got to the same conclusion