Homebuilt PC shuts off after POST

[rocketgirl]

My husband and I (with some encouragement from friends) built our first PC nearly 2 years ago. The computer began shutting itself off randomly some time ago (I don't use it very often as I have my own laptop). It would always start up again fine. It is now shutting off after POST. Eventually, we can usually get it to fully boot. Each time we attempt to turn it on, it will get a little further until after 6-8 tries, it fully boots, most of the time. One time, it would not boot and we got a black screen saying we had a corrupt system file. We used the Vista disk to boot from and do a repair which seemed to get it going again, but it still shuts off.

Basic system specs are:

CPU: AMD Athlon 64x2 (sorry, I can't remember the specific model and I'm not at home right now)
Mobo: ECS GeForce6100SM-M
PSU: CoolerMaster 600W
RAM: 2x1GB Corsair PC6400 800 MHz DDR2
GPU: Palit ATi Radeon HD 3870 512MB DDR3
HDD: 500 GB (I think it's a Seagate)
OS: Vista Home Premium 32-bit
Case: Coolermaster with 3 case fans and a side panel air duct

Things we've tried that haven't worked:

*replacing the surge protector
*tried using the reset button as the power button
*reseated memory, trying one stick at a time
*replaced the memory
*replaced the PSU
*reinstalled Vista (took two tries as it shut off on us the first time)
*reseated the CPU and heatsink (CPU looked fine - not burned - we did clean it with Arctic Silver thermal material remover and purifier and replaced the thermal compound)
*reconnected each component, checked all connections, dusted each component, fan and case

All fans appear to be operational. Nothing looks amiss on the motherboard (no leaking or bulging capacitors, nothing looks burned). The CPU is not running hot (according to Speedfan). We could try replacing the HDD, but it doesn't seem to me as if that would cause the power to just cut off like it does...or maybe it would?

Any suggestions?

Thanks!

 

[AMDThunder]

Since you already replaced the PSU, my first guess is a bad mobo. ECS isn't exactly considered top tier. There's a sticky thread you might read for help troubleshooting. It should walk you through everything. Might also check the thread on breadboarding. Possible you could have a short somewhere. Was the PC moved recently?

 

[rocketgirl]

It hadn't been moved until it started doing this. It's been moved a lot within the past few weeks.

 

[AMDThunder]

Something could have come loose and be causing a short. You need to breadboard it to be sure. Basically you're taking everything out of the case, and setting it up on a piece of cardboard. We know it will post, so you may not need to strip it completely down. Taking it out of the case will insure there are no shorts. I'd start with only the hard drive and one stick of RAM to see if it gets past the POST. If it does, add your vid card and see what happens. I wouldn't think it would post if it were a short, but its a good place to start regardless.

EDIT* Because I can't type worth a crap.

 

[Hard Line]

I , too, am inclined to suggest mainboard at this time.. as was said previously mentioned my first thought was ram or psu but you replaced them.. and I agree about ecs.. I don't use that brand because of the reputation they have

 

[rocketgirl]

Yeah, the ECS was a risk we took as it was part of a combo deal with the CPU from Fry's. I have never breadboarded a computer before, but I can give it a shot. I'm a tad freaked out by having to turn it on without a button though. Could I buy just a power button separately to plug into the motherboard?

Do you think the possible short could be within the case wiring?

I am leaning towards a motherboard issue, with my inexperienced observations. 😉 We have also had trouble with the sound cutting out on our speakers. Not sure if it's the motherboard or the jack on the case causing them to not work at random. And, our DVD drive will sometimes not be recognized. We've found that disconnecting it and reconnecting it seems to bring it back online.

If the motherboard is dead , the debate we will be having is whether to buy just a new motherboard or "rebuild" with new motherboard, CPU, memory and graphics card. Sigh...

 

[redgarl]

Since you already replaced the PSU, my first guess is a bad mobo. ECS isn't exactly considered top tier. There's a sticky thread you might read for help troubleshooting. It should walk you through everything. Might also check the thread on breadboarding. Possible you could have a short somewhere. Was the PC moved recently?

Bingo, your mobo is dying. Mine was unable to find my hard drive half of the time when I was powering up my PC.

Motherboard are what that caused me the most repair. Some boards are really badly designed, my Gigabyte 965P-DS3 died on me 3 times in less than 16 months.