comp crashing problem need some advice

[timebecomes]

First here is the system:
800 mhz thunderbird (not overclocked)
epox motherboard (not sure of the exact model)
256 meg crucial c2 pc133 SDRAM
generic ethernet card
generic floppy drive
quantum fireball 40 gig 7200 rpm HD
delta 12x dvd drive
plextor 16x10x40 CDRW
probably a 250 watt power supply
Running Windows XP professional

Here is the problem: It will randomly freeze on me after it has been on for a while. There doesn't seem to be a pattern of time when it locks up or not, sometimes it will go 2 days straight, and sometimes it will freeze after an hour. I run the THINC program for researching cancer all the time, which would tend to increase cpu temp, however it stays well within normal range, and both fans in my case are working, so I don't think that it is a temp thing. The starngest part is that after it locks up, if I turn it on again immediately, it won't post anything on the monitor. If I wait about 30 min-1 hour it will post just far enough to see the ram check, and then stop. Over an hour and it usually starts working fine again. It locks up in all situations to, if I'm playing a game, or playing mp3's, or just letting it sit. Help would be much appreciated. I will offer any more info that you may need. Thanks much.

 

[Machupo]

you may want to load up motherboard monitor or some other program that will enable you to see the voltage levels on your 5v and 12v rails... most of the athy's i've played with (with the exception of the new XP's and MP's) have freaked out on me when i put them in bed with a 250watt PSU...

just something to check on

you can snag mobo monitor here

 

[DaiShan]

I take it that this isn't a custom made computer, who makes it? what model is it? are you running any usb devices? do you know if it is a via chipset?

 

[Mooligan]

Id almost be suspicious of the powersupply..if its a cheapo case, then cheapo PS, 250W to boot..

 

[timebecomes]

Actually it is custom built. I put it together myself last early last year. It jas worked fine before about a month ago when it started freezing up. The case was a fairly cheap one, which would obvioulsy make the PS cheap as well, but would that really make that much of a difference? Should I try to go find a 300 W PS and test that to see if it's stable? - Thanks

 

[timebecomes]

I also downloaded the mobo monitor, and quite frankly, I don't really know what a five V and 12 V rail is, but in the 15 min before my comp bit again, the voltages looked like they were very close to the expected. Within .02 or so.

 

[DaiShan]

since you built it, is there anyway we could get the specifics on it, exact brand and model of the psu, also same for the mobo, would be good to know which chipset it runs.