Bootcamp gaming lag Windows 8

Specs:

27-inch, Late 2012

3.4Ghz Intel Core i7

32GB 1600 MHz DDR3

NVIDIA GeForce GTX 675MX 1024 MB

Hello all,

I've been researching this issue and haven't found many helpful threads for the iMac. The title basically says it all. I've installed Windows 8 via Bootcamp to game a little bit and it runs great on med-high settings for about 20-30 mins, then starts lagging and gets substantially worse as I keep playing-- even after switching to the lowest settings! I've installed the latest gaming drivers from Nvidia, which is the most popular 'solution' but that didn't help the problem at all for me.

The Nvidia software suggests that my computer should be able to handle Ultra settings and I don't understand what's happening here. I should also note that I've tried my Windows 7 copy with the same null results and I'd prefer to keep Win 8 because it allows for the full 32gb RAM I have installed.

I've read that the issue may be the computer throttling the graphics to prevent overheating, but shouldn't it be able to handle more than 20 mins? I don't know a ton about graphics, over/underclocking, or drivers, but I'm open to try any and all solutions.

Any advice on the issue would be much appreciated. Thank you!