I received a used Dell Dimension 8300 as a gift after my last computer broke (was 100% custom built by a family member as a gift) and I transferred over my parts:
3.4Ghz Processor
500watt power supply
Sound blaster Audigy sound card
GeForce 7800 GS
3Gb RAM
Nothing too fancy but it does the job. I just installed the power supply after having issues with "low battery" errors and random crashing. Realized it wasn't the problem so I replaced the CMOS battery. Fired it up and it ran great for about 10mins and shut off. Started it back up and it said it crashed "due to a thermal event". The heatsink was hot to the touch but the case fan was working.
I'm going to pick up a can of air and clean out the case since it's been sitting for about a year and going to add new thermal glue to the heat sink. What else can I do to fix this? Can I upgrade my case fan? Can I get a factory-style dell heatsink with a fan? Where do I plug in the new fan? I'm a noob when it comes to building PCs so any help and links would be awesome. Also, all my settings are default and I'm running Windows XP.