New CPU Cooler = unstable PC?

I haven't used prime95 yet, I definitely will give it a go when I get home this evening. idle CPU temps are 31 to 33 celsius.

Did you use thermal paste?

What PSU, make/model? What graphics card? What S/W when restarts?

Mike.

Thank you all. I did use thermal grease. The cooler I used is:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
this is the thermal grease:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

it's a lot better than the crappy aluminum cooler that was on there. graphics card is a Radeon 8500.

Full specs, please.

(Radeon 8500? wow.)

sorry, it's this one:

http://ati.amd.com/products/radeon8500/radeon8500/index...

Did you mount the HS correctly? If I remember correctly if it is mount wrong the cooler will contact the socket and not get full contact on the CPU.

Otherwise I would think it could be a problem with you graphics card or PS.

what happened was my CPU fan broke, and an alarm went off and my computer shut down, I opened it and saw that the fan was spinning in spurts, I bought a new fan and a copper heartsink (the aluminum one that was on there was very cruddy) I installed it with thermal compound, the new cooler went in easy, I read a lot on how to do it first to make sure I was educated about it. Now, the above described symptoms are happening, it's a different kind of shutdown, there's no heat alarm, and it restarts, it doesn't just turn off...it happens whenever I run any kind of 3d application.

Perhaps you accidentally touched and moved a capacitor a bit. I messed up an old mobo doing this, check if your capacitors near your cpu socket are good and are not bloated/leaking, also other general components mounted on the mobo?

do you think that would allow the PC to function until a game is started and then crash...?

well, I've had prime95 running for about 4 or 5 hours and my CPU temp hasn't risen above 36 Celsius. I'm starting to wonder if my video card is shot. It just seems like a coincidence that it happened right when I changed my CPU heatsink.

Have you tried another PSU? Just to rule it out? Makes sense as there will be more of a current draw from it while playing.