Well, my computer's processor stays at about 33 degrees Celsius idle and will go to about 50 degrees Celsius under a load (like playing a game) while the maximum for my specific processor (all are not the same) is 70 degrees Celsius. I've overclocked it from 2 GHz to 2.2 GHz.
My motherboard temperature stays around 30 - 37 degrees Celsius all the time. That's okay.
My graphics card runs extremely hot; probably hotter than anyone else's here. It runs at 60 degrees Celsius idle and 98 degrees Celsius while running Half-Life 2. Can't wait to break the 100 degree barrier!
(Just kidding...) It can tolerate temperatures up to about 120 degrees Celsius, but I would never let it get that hot. I don't think it is going to go past about 98 degrees though. No artifacts yet either! And I mean none! It's a warm little device, my video card is.
My hard drive hovers around 28-31 degrees Celsius; nice and cool...
Obviously if you have a laptop or something the maximum temperatures will be higher. For example, the maximum temperature on my Turion 64 laptop processor is 95 degrees Celsius. The maximum for the hard drive is about 55 degrees Celsius, as well. As for the graphics card, I don't know, but I'm curious so I'm about to download RivaTuner to see what it runs at typically. Should be interesting... I'll let y'all know.
EDIT: Ah, nevermind, I can't monitor it and RivaTuner is, of course, only for Nvidia cards (D'oh!
). So, nevermind about that, it'll have to go unknown.