Random computer shutdowns?

[Lonyo]

Sometimes my computer will shut down totally while in the middle of something, with no explanation.
I was playing The Sims 2 (well, kind of). I had gone to create a character, and when I clicked to finish creating, my computer shut off.
It did this twice, at the same point as I clicked create character.
It sometimes happens, but not often, during UT2004. It's very rare that it happens, and it doesn't happen in HL2 either. I consider these more demanding than Sims 2, so I don't know what the problems is.

I also have some memory issues, where programs, after I click close, give me errors as they close.
I have a 512MB stick of ram and a 256MB, the 256MB stick is overclocked, and this map be the problem, but would it cause the whole system to shut down?
(I've got an Enermax 420w PSU running a mobile Barton and 9800, nothing too taxing)
I'm thinking of getting some new RAM (to give 512x2).

Does it sound like overclocked RAM would cause the system to shut off totally under some situations?

 

[mechBgon]

Possible reasons, at first glance:

[*]Audigy clashing with onboard MIDI/Gameport/Audio/Firewire features as the case may be, or simply clashing, period. What PCI slot is it in, one of the center three slots hopefully?

[*]Overclocked memory. Well heck, try taking it out

[*]Possibly the memory wants more voltage? Kick it up a wee bit if it's scraping along on AUTO (2.5 volts)

[*]Heatsink on backwards? third & fourth photos here and if you've got a Thermalright clip-down heatsink by any chance, check the TR-specific tip there. Other causes of poor core-to-heatsink contact could do this too (shims for example).

Hope the problem comes to light for you

 

[LED]

Sure the RAM could be the problem...usually it'll go BSOD but not necessarily. What the FSB you cruising @ on the 2100 and you could set the Latency to 3 or a slower setting ...

 

[Lonyo]

I don't use the Audigy I have, but it's installed. I may try removing it.
Mem voltage has been cranked up to 2.8v or so.
I'm running a stick of PC2700 C2 at 190MHz or so. A friend got it up to 210MHz he said.
Timings are lax, 2.5-3-3-11 I think.

I may try without the RAM in, or without Audigy in.
If it's the RAM, I'm not bothered as I want to replace it.