I've got an HP Pavillion running Vista 32-bit that's about 3 years old now. Last summer, I had it crash a couple times when I really pushed it in hot weather (running Warhammer 40k II at high visual settings in a warm second story room). This year, it's crashing at a much lower temperature and during less intense usage (running KotOR II on medium settings in same room on cooler day). I'm fairly certain this is a heat issue. Running the same programs during the colder months of the year never causes a crash. I've run games all afternoon in the winter with no adverse effects, but it crashes after an hour max in the summer, I think because the room is a few degrees warmer in the summer. However, I'm not sure what is overheating, how to determine that, or what to do when it is determined. Right now, I think my main suspects are the CPU, the power supply, and the video card. Whenever I run games or try to run a number of processes at once, the processor fan spins up and sounds like a jet engine. I don't even have to hit a very high % of my full processor speed to get that response; 50% is often more than enough. However, even after a crash, the heat sink isn't especially warm to the touch. The power supply is simply warm. It's not roasting hot, but it gets fairly warm to the touch on the outside, so it could be much warmer inside. I don't know that this is a problem, though. The video card fan gets really hot really fast even during normal, non-graphics intense usage. The fan runs, but based on the heat, I'm not sure it's cooling the card sufficiently. Now for specs. The processor is an AMD Athlon 64 X2 Dual Core Processor 4800+ at 2.5 GHz. The video card is an NVIDIA GeForce 8400 GS. The power supply is a Bestec ATX-300-12Z, 300W. So far, the only thing I've done is give the computer a number of thorough dustings. I've even gone so far as to remove the processor fan to completely clean the heatsink. I'm wondering too whether I might be having trouble with ventilation in general. The case has the power supply fan, one fan pulling air out near the processor, and the processor fan trying to pull air through a nearby vent. I'm wondering if I need to replace fans or find a way to rig more fans (the case doesn't have any more places to mount fans). Any ideas as to how I can figure out what's wrong and how to fix it? The other problem I'm having is with RAM detection. I have four 1 GB sticks in the computer, but the computer only registers as having 3326 MB when all four sticks are in place. If I remove one stick (doesn't matter which stick or slot) I drop to 3070 MB. I swapped sticks and slots around, and any three sticks in any three slots always equals right around 3 GB, but the fourth stick will never register as a full GB. Two sticks came with the computer. Googling the serial number says they're Qimonda RAM, 1 GB DDR2 SDRAM at 333 MHz. The other two sticks were purchases separately. They're OCZ DDR2 PC2-6400 Platinum Revision 2 Dual Channel, 800MHz. All sticks are 1 GB. This isn't as big of an issue as the overheating, but I'd still like to figure out why I'm not able to utilize all my RAM. Any help would be much appreciated.