Pretty sure my pc is overheating

Ok, I recently got a new pc, and I'm enjoying it tons.
Quad core, 2.4ghz per core.  nVidia 8500gt, 3 GB ram.

This happened three weeks ago.
I was playing garry's mod, and then fan got very loud, then the computer shut off.
I suspected this was overheating, and blamed on the intense particles I was rendering at the time.  To my surprise, it did this all day the next day no matter what I did, browse the web, chat, even idle.

Then it just sort of stopped.

Now it's starting to do it again, and it's quite a fucking pain.
Any solutions?
Also, IS this actually overheating?

something stuck in your fan, stops it from cooling properlike.  probably a poorly tied cable or some shit.  remove it.

computer automaticably shuts down if temperature gets too high, before overheating causes damage.

I checked, the fan's spinning properly, and the air it's blowing out is cool.

just get a new fan, cause it sounds like the whole thing is off balance and vibrating

Well, the pc is brand new, I'd hate too. :x

>>4
He probably means that the fans just spun up to max speed.

Next time it crashes, check and see if any of the heatsinks on any of the chips are extremely hot.

That'll be your culprit.

If there isn't any that feels hot, it's probably a power issue.

could be a faulty temperature gauge.  says it's overheating, but it's not.  stick your tongue on something, if it burns, it's overheating.