I made this computer back in 2009

Radeon 5670 HD 1gb
Phenom II x2 BLACK edition 3.2ghz CPu
4gb ddr3 corsair ram
450W PSU

For the last year or so, WHENEVER I play games intenstly online, ie: running dungeons or MASS events in guild wars 2 with tons of other people, my cpu goes to about 96 degrees celcius then shuts off.....As I'm typing this right now my cpu is at 30 degrees celcius....so what do you think I need to do?

I talked with some buddies online and they said I need to replace my thermal paste with arctic silver thermal paste and I should be good to go.

Should that do it or would I need a bigger CPU fan? if so which would you recommend? I have not overclocked my cpu or anything, so why is the stock fan not doing a good job?

I have a thermal take case and its pretty breathe happy.

I have cleaned the computer inside of all dust and I'm still having this problem.

thanks!Also its weird cus I dont overheat during skyrim and other games, only mmorpgs.It's possible that the thermal paste has dried up or is otherwise not doing its job properly.  How soon does your CPU overheat?  Is it pretty instant, or does it SLOWLY climb to that temperature?
Try a CPU stress test, such as Prime95 - download it here, extract it, run the PROGRAM, answer "just stress TESTING" and hit OK.  Monitor your temperatures in the test and see what happens.  What program are you using to monitor the temperature, by the way?  I find Core Temp is best for AMD CPUs, although hwmonitor does a fine job too.