I just finished building my new gaming rig, which consists of:
Intel i5 3570k quad core processor @ 3.40GHz
Nvidia GeForce GTX 680
However, with this new rig (which I thought would probably be able to pretty much destroy any game on ultra), I am having strange performance issues (aka lower than expected framerate), in World of Warcraft, DOTA2, The Witcher 2, Diablo 3, amongst other games. I have reinstalled drivers, and made sure GPU fan is high enough so it isn't overheating. Anyone please have any ideas why I could be having performance problems like this? Thanks in advance.
You may need to first adjust your expectations. You can't just turn all settings to "Uber" and expect butter smooth FPS...even with your specs. However, it is not hardware tech that is the issue, per se. It could be program optimization that is choking your performance. Most games still aren't optimized for multi core cpus, drivers not updated to support game engine updates, AA/AF & high rez textures hitting big on performance, etc...
Try tweaking the games' visual settings individually. start low, then scale upwards one level at a time (resolution, AA, AF, shadows, etc.). Make sure you dont have other (un-needed) background processes running, as well. As long as you are not crashing/BSOD'ing I wouldn't assume hardware. Low FPS is usually indicative of a processing choke point.
My PSU is 900W. I'm using stock cooling on my graphics card and CPU at the moment, although can install a water cooler on my CPU but I don't know if that will help the situation. Here is a link to my benchmark result on 3D MARK 11: http://www.3dmark.com/3dm11/4265209