Is there any sort of program I can run that will track the performance of all the important parts of my computer or something, and save them in a file that I can open up after my computer fails?

I've begun having the same problem again, where my computer randomly shuts off during games like The Sims 3, Starcraft 2, and L4D2. I took it to a repair shop, and they had it running on diagnostics for a weekend straight and couldn't find a problem, they couldn't make it crash. But when I play these games, occasionally the whole system just randomly fails. Starcraft 2 worked perfect again there for a little while, then randomly the computer failed a night or two ago while I was on it. Now it's working again supposedly, because I played it for like 45-60 minutes without crashing the computer. Then today, my sister tried to play the Sims 3 on it, and within moments the whole computer crashed again. It's aggravating because the tech people at the shop don't have a clue what's wrong with it, nor do I, and they can't seem to make it fail. They told me it seems like it's in perfect condition, which clearly it is not. So is there anything I can run that will be able to tell me what's failing on my computer at the time of crashing?