To further confirm the computer temperatures above, here's a reading from SpeedFan
Last but not least, my power supply.
5 and 3.3 V combined load 230W
5 and 12 and 3.3 V combined load 422W
Total output 500W max
My case is pretty clean since I just cleaned out the dust. I don't know if it's a heat issue b/c I just installed 3 new 80 mm fans (1800 rpm), two exhaust in rear and one intake on side. I already read somewhere that 500W is pretty good for power supply.
It shuts down when I play games like Team Fortress 2, which isn't that intense with graphics since my laptop with integrated graphics can play it. Also my computer can withstand intense graphics, considering the GT 430 i installed in it.
Either way, it still shuts down. Like no blue screen or anything. Just shuts down. and when I turn it on, it says that Windows didn't shut down correctly, stuff like that. My video drivers are all up to date. It completely shuts down, not just the monitor.
your processor is old, tired and slow. pull the heat sink and fan. clean up the old thermal paste and reapply new. re-seat heat sink and fan.
the memory is running at some really odd speed. that would be the first thing i would look at. go into the BIOS and check that ( make it run right ). what speed does it say on the side of the ram ?
there is absolutely no way that machine can run anything comfortably at that high of a resolution. turn it back to 1024x768 and see if that helps...... or another lower resolution the monitor will run at.