ATI2900XT no monitorsignal + computer shuts off after applying thermal paste to cpu

[Legoflamb]

Sorry for the cross post but I'm not sure whether I have a cpu or graphics card problem.

Ok So I built this computer nearly 2 years ago and it's generally been very good.

Yesterday when i was putting the system under a lot of stress it decided to turn off and when turned back on it said that the cpu had overheated. So I thought I'd tread carefully and only use it for a little while and then put some more thermal paste on the chip and clean any dust out of the heatsink.

I did this and re-seated the heatsink and now when I turn on the computer th e monitor says no signal and sometimes now after about 20 seconds the computer turns itself off. The monitor saying no signal is always happening.

I have:

Q6600
Asus P5B-VM SE
ati HD2900XT
Enermax 650 noisetaker I
Win xp
2gb corsair ram
Maxtor 500gb HD

Literally all I did was take the heatsink off, clean it, add new paste and put it back on, nothing else in the computer was interfered with. Has the graphics card mysteriously decided to pack up even though it said the cpu was overheating?

I'm at a loss - I've made sure everything is in properly and taken steps to stop cpu overheating.

Thanks in advance guys.

 

[Tmagic650]

Did you clean the old paste off before applying new paste. Did you use too much paste? Too much paste will act like an insulator and cause the CPU to overheat. Also, if you used a grey or black paste, it is conductive and may short out the motherboard if it comes in contact with it...