What could be making my puter shut down?

[Bloodbone]

It is a home-built,my first.
It has started shutting down periodically,and rebooting,after maybe 5 minutes of use.
This is while being way lower than the Via monitoring system says is overheat range etc.
1.4 gig Thunderbird
Iwill KK 266 Mobo
WD 40 g hd
Sony cd drive
Teac burner
Iomega zip drive
Voodoo 5
Win 98 SE w/ ME upgrade

I loaded a bunch of utilities recently,like benchmarking stuff,but I don't know enough about what it tells me to know if it is good or bad.
One thing-the puter will not get all the way through with 3D Mark 2001 without freezing up.
What can I try?
Thanks.

[rextex]

What does the votage reading say, and do you have the hardware monitor set to shutdown at a certain temperature?


--Anyway here's a site with a lot of stuuf about that board and more:
http://www.x-faqtor.com/KK266.htm

[Commandos]

you didn't mention anything about the RAM and PSU. My friend had the same problem and there were a faulty RAM and weak PSU.

[Bloodbone]

It's 512 megs generic PC-133 RAM.
Haven't checked the voltage yet.

[ukulele]

Suspect the power supply first. Weak capacitance or minimal output in the power supply can cause reboots if your line voltage drops when ever another appliance or device is turned on in the house or just plain dirty power from the pole. I live far from the powerplant and have long wires from the pole. I have owned several computers that didn't like the junk power in Hawaii. A bigger and newer power supply has worked wonders for stability. An UPS might also help if you notice the lights ocassionally dimming. If you have done that, been there, suspect the ram next. Good Luck

[Bloodbone]

Well,I'm thinking it must be that generic RAM.
I pulled that out,and swapped in a stick of Apacer 128 that I had laying around.
Seems to have cured the prob.
Went ahead and ordered a 256 stick of the same Apacer.
Apacer=good.
Generic=bad.