The stock Dell heatsink gets gunked up with dust pretty quick. I've pulled dust ELEPHANTS (as compared to dust bunnies) out of Dell cases before....

For being such crap, Dell computers are suprisingly good machines.

yeah they are good, mine has never had any problems that i didnt cause. the heatsink is now spotless, honestly i dont think the fan is keeping up with it right now, and it just has that stupid thermal pad on the bottom of the heatsink, so who knows how well thats workin

I think mine is an Optiplex GX260. My previous statement was based on the fact that, while it works and runs great, come of the components are basically crap in my opinion. And the fact that the motherboard is proprietary. I actually bout a new case for mine last year and ended up having to sell it because I couldn't use it withe the Dell MB. I can't increase my memory past 512 either, because any higher than that requires Dell branded memoery.

If you have an aftermarket heatsink and fan, I would definitely suggest popping that on the CPU. Testing the memory wouldn't hurt either. But from what you've described, I'd put my money on the CPU

What is the CPU and system temp? It should be in the BIOS.

I support thousands of Dell PC'* at my work. The one major hardware problem that we find with those PC'* are with the PSU'*. I've seen so many power supplys fail on those machines.

Just something to think about...

And furthermore (I used to do tech support too before my Sys. Anyl. job now) is that a defective device such as a CD-ROM drive can rob wattage from the power supply and not supply enough power to the mobo and CPU, causing no boot ups or a reboot at random times. I've witnessed that happen with a bad CD-ROM drive.

I've got a Dell Dimension 4000 or something....anywho, both times it started rebooting itself just for the hell of it, it turned out that the CPU fan wasnt working properly. The first time it was under warranty and a guy came out and fixed it and then spent like an hour "tweaking" my system settings. :? This last time, I went to Office Depot and bought a copper heatsink with a new fan...which is kinda loud, but no more problems. I used to have all kinds of problems before I upgraded to XP last fall. Since then the only issue was the CPU fan. Which is good because I would rather spend money on mods for my car and not on a computer. Spring can get here any time now.

well i followed MOS'* idea and came home and lubed up the CPU fan, and now its running fine, has been for over an hour, and i ran it at 100% for id say at least 15-20 mins...so its working now, i think im going to put the other heatsink/fan on though, im supposed to get some thermal paste from a friend of mine tomorrow, i just think the fan sitting directly on the heatsink would cool better than that crazy ducting thing....i might rig up something to where the ducting stays on there a little bit though, cause itd make a nifty exhaust fan...

i also tried messing with the memory, but it still restarted, so the memory is fine.
my Dell has alot of weird parts too, and just some weird setups in general. ive never like the ducting system, and i cant add another HD without some sort of fancy bracketry, which i dont have, so im stuck with one, unless i want to just let one hang in there, either that or remove my floppy, which about the time i do that ill need it.

my Dell supports up to a GB of RAM, i have 640 in it now, and as cheap as the stuff is getting it might see a gig before the summer is over, and then my old linux machine will be hauling balls with 256 baby!

thanks for all the suggestions and the help, you guys rule.