Hey everyone. I'm not writing to support because this isn't strictly a GoG related problem, and it's a problem that's really got me scratching my head. Unfortunately, I can't play any games until I resolve it so hopefully one of you guys can help me.
It only happens when I'm playing video games. The computer will shut off without warning; no fragmenting, artifacting etc...it's as if I just pulled the plug on the computer. I originally figured my power supply was going bad so I replaced it with a new one, but the problem persists. This isn't a new system, I've had it for a year and this problem only started a few weeks ago. Any ideas?
8800 gts 512mg
2046 RAM
Intel Core 2 Duo 3gigs
WinXP serice pack 2

You graphics card may have two temperature zones, 1 for the GPU and 1 for the VRAM, or more likely, "Temp 1" refers to a motherboard temp sensor, probably the chipset area of the mobo (assuming you also have a separate entry that is already labeled "CPU").

When I first installed SpeedFan the temperatures were also titled in a weird or even wrong way. So even if you still don't know which temperature it is, as long as that information is correct something definitely seems to heat up more than it should. So I'd also say that you should just manually check what is overheating that much.

Have you thought, as a base measure to go into the bios and look at the page that gives various temperatures and leave the PC running for an hour and seeing if there are any changes? Assuming the numbers are constant, you have a base figure to work from.

I'm afraid that won't do any good - he needs a reading while his CPU is being used, not when it's idle ;)
(I see you have a -1 reputation, so you got a +1 from me ;))
As for the original problem - temperature aside, what's are your PSU's specs? You have a pretty demanding system in terms of power usage, so PSU would be my first suspect. I had a similar problem after changing my video card; my computer would suddenly power down or reboot for no apparent reason. As it turned out, PSU didn't give enough power to keep the system going :)
Other solution - check for dust inside your case (if it's temperature related) - your fans might not work fast enough to cool the system down properly.

Yes, I understand that. But without a base measurement at idle, how meaningful is any other number? If my Cpu is 68c at ide, 72c is okay at full pelt, but if all I have is the 72c figure, what does it mean? That was what i was trying to get at. If, for example he found out his cpu was 94c at idle, it would explain the 100c with speedfan, but now the speedfan number wouldn;t matter, because he'd already know he had a problem via the bios! :)

You don't need a base measurement, only at what temp it goes ping. Doesn't help or make an iota of diference if the "base" temp is 10 or 150 degrees, it's what happens when it's under load that matters.
I have a suspicion it's the GPU fan or the thermal cut out set too low in the GPU propertiens. You won't experience any graphical glitches just a cut out for temp problems or seating problems.
Firstly, remove the graphics card and reseat it again, due to component creep the thing may have worked it's way loose. As it heats up a conection is lost and poof, gone, check the connectors to everything on the graphics board and ensure all the tiny wires are all connected properly. Have a peek at the conectors along the slot too, if any appear to be blackened you know it was due to component creep, a quick rub with an eraser and you're sorted.
Run the computer with the case off and see it the fans are up and running, see what happens when the game is started and the GPU starts to earn it's crust. If the fan does not start or stops as it heats up, fine and dandy you know it's the GPU fan, easy enough to replace.
Do you get any error messages when it reboots?

Trust me - if the base was either 10 or 150 at idle, I would switch off the PC damn quickly!!!! :)

i had a similar problem, and i definitely think that your case/GPU temperatures are way too high. you may have already done damage to your graphics card at this point, too. hopefully you're still under warranty -- if so, i'd get a replacement to see if that helps.
additionally, i think you should invest in some case fans. that fixed my problem -- i added three case fans and now my graphics setup (dual 8800 GT cards running in SLI) runs fine -- no more immediate computer shutdowns.

Not being funny but, we're trying to help the guy and you're asking things like, whats' the base temp? Which kinda makes people believe that you haven't got a clue.
It doesn't matter what the "base temp" is as it does not start to go all wrong till the computer starts to work for it's supper. The poster said everything is fine till he starts playing games, there's the biggest clue on the planet and you missed it!
Go away.
There is no such thing as a "base temperature" only a reading at that moment in time.

to be fair to uk john, i'm sure he meant the computer's idle temperature when he said "base temp," and that is important. the problem arose when the OP put his computer under load, i.e. playing games, but it's important to know what the idle temp is because the problem could related the case's airflow or lack thereof.
the OP said that the idle temp is 58 degrees C, which is really really high. my computer idles around 40 degrees C, and goes up to about 50 degrees under load. if the OP is idling at 58, i'd say that his case temp is getting too high, causing other components to overheat. he'd have to add cooling to the case, in the form of additional fans or liquid, in order to fix this.
plus, it's never helpful to tell another person who's just trying to help out to go away.

I was thinking of something else but refrained.
As you may be aware seeing as you seem clued up anything below 60 is also acceptable on some PC's, depending on your set up. There isn't really an average CPU idle temp.
Also if the PC does not go off when under load with the case sides off then the airflow is restricted but I was saving that bit for later on

I know you already switched power supplies, but is it possible that the PSU is underpowered and you're not getting enough power to some components?

Clagg, you are the one who is coming off like he doesn't know what he is talking about. Each individual PC does have a base or idle temp range that it normally runs at when not under a heavy workload. It is different for every PC, but there is a temp range that most PCs will fall into and knowing what a PCs idle temp is can help determine if the workload temp is way out of whack. Additionally, if the idle temp is unusually high, it can point to other issues beyond the video card, like the case airflow problem you mentioned. There is absolutely no need for you to be so rude when UK_John was asking a legitimate and pertinent question about the problem at hand.

Hey guys. I seem to have fixed my problem. I took the processor fan off, cleaned it, reapplied the thermal paste, now it seems to be working fine. You all helped me alot and I appretiate it greatly. I gave the solution point to Bicro because when I opened it up, I wouldn't have noticed that the processor fan was indeed a little loose, unless he had mentioned it here.
But thanks again for all the great replies