Computer freezing

Been going on for a while. I have a dual monitor setup running WoW in one and using the other one for YouTube or surfing the net.

I was having an overheating issue so I installed a hyper 212, bought a new gpu, and installed new power supply (850W corsair). Computer at one point was shutting down randomly, new PSU seemed to solve that.

Problem is when I'm playing wow and I load up the other monitor with Firefox everything starts slowing down. WoW starts to freeze up and slow down and it takes a min or two or five for everything to catch up. As soon as I search something or click a link this process starts all over. Sometimes Firefox goes blank and running the mouse over it text will pop up highlighted and then everything catches back up again.

Is this a RAM issue? Would switching to windows 64 bit help? I ran windows memory diagnostic test and it found no errors. I did notice my DRAM says 665.1 and I have corsair 2x2gb 1600mhz.

Any help would be appreciated, getting frustrated with it.

Msconfig > startup

Make sure you dont have any programs running in the back round that you dont need on start up, that are using alot of memory

Maybe try using new RAM sticks, or maybe Firefox is the issue? Try Google Chrome to see if it makes a difference.

Verify also that your system is not getting too hot. If computer parts get too hot you can have performance issues.