PC restarting

Hello , I need help my PC keeps restarting when trying to play TBC on the Outland server. I was able to player for over an hour on launch then my PC restarted twice while in the game. Ive troubleshooted as best I can it doesnt seem to be on my end!!!! I can play every other game on my PC. I did have a ****ty cpu cooler on there so I bought a new one and temps are good but as soon as I loaded your server INSTANT PC CRASH LOL!
I need help. The only thing I can think of is im using VOA 2.4.3 download the starting guide didnt specifically say YOU NEED OUR DOWNLOAD!

Update 1 :
I updated my graphics drivers and redownloaded and installed the game. STILL crashed within minutes in the live server. It didnt seem to crash while waiting in queue for 20-30 mins.

let me know thanks.