PC Powers down intermittently

[YoMax]

I updated my equipment with a new case, mobo, and cpu, keeping everything else (all else works fine). Since upgrade, my system will dump power without warning. It may happen after 10 minutes or 10 hours on. Pushing the ATX front panel power up doesn't turn it on again, you have to turn the power supply switch off, then back on, then everything boots ok.
I also noticed that a couple times it lost power when the case was bumped, suggesting a loose connection or something. I tried removing the mb and checking connections, standoffs, everything, and putting it back together, same problem. I borrowed an Antec 300W supply overnight and didn't have a power loss, but I had to give it back, so I'm not sure the ps is the problem, but maybe?

Mid Tower Case w/300W generic PS
K7S5A System Board
Athlon 1800+ retail, using provided cooling.
Diamond Stealth III 540 PCI video
Maxtor 11.2GB
50x noname CD
Memory, 128mb SDram pc100 (Micron Crucial)
Memory, 256mb SDram supposedly pc133 bought at computer show
(Problem occurs with either or both sticks).
I haven't installed anything else yet, wanting to keep the problem simple. Cooling is good, with several fans keeping the cpu temp below 120F.

BIOS settings, have tried changing a few of them, but mainly set for low-performance (100/100 on the speed setting for example).

I suspect the PS, but thought I'd get some opinions before I buy another, since machine is mine and no hurry.

Any ideas folks?

 

[Skark166]

I suspect you are correct on that. It sounds like there is a loose connection within the power supply
Scarecrow

 

[2ndtonunn]

I agree with Stark the power supply is the most likely cause - not all power supplies are created equal, take a look at the AMD website at their recommended power supplies, if you decide to replace it I would go for a 400 - 450W that will allow more headroom for upgrading later, you only want to buy it once!

 

[YoMax]

Thanks 2ndtonunn and Scarecrow. Last night I think I proved it to be bad PS; removed it from case and isolated it physically so I could tap on the supply without any vibrations reaching the case. A gentle tap on the PS and bingo! system powers down. Every time I brought it back up a slight tap killed it, so you guys are right on.

By the way, if someone is having this sort of problem I'd recommend only booting to the BIOS setup screen to troubleshoot, because you'll eventually scramble your Windows files otherwise.

 

[Grenage]

Could always open it up and find the loose connection, save you paying for a new PSU anyhows.

 

[madonnac]

something to check out (I've had the same problem) - check for screws, etc beneath the motherboard

 

[Ssshaker]

Not a good idea to suggest opening up the PSU Grenage. If you don't know what you are doing, sometimes the caps retain enough voltage for days to kill and having an inexpert poking around in there is not good.

 

[Ssshaker]

Buying a brand PSU is the best idea but even they fail too. Surge protection (UPS) is also recommended.

Not a good idea to suggest opening up the PSU Grenage. If you don't know what you are doing, sometimes the caps retain enough voltage for days to kill and having an inexpert poking around in there is not good.

 

[YoMax]

Thanks again to all for the suggestions. The PS from the new case is definitely bad, and the local shop who sold it to me has agreed to exchange the supply.

 

[Grenage]

Yes your quite right of course

although if you do want to open it up remember to leave it unplugged for 48 hours before you open it.