Windows 8.1 random freezes, BSODs, and screen shutoffs

Hi all, I recently upgraded my graphics card from a geforce 9500GT to a GTS 250, installed the appropriate drivers, and now im having strange problems. Before upgrading, I did get an occasional BSOD but not enough to really cause a problem.
This happens mainly when using metro apps. It will lock up, than the screen shuts off as if I just shut off the computer. There is nothing in event viewer except a kernal-power error which natrually occurs from restarting improperly. Aside from reinstalling the OS I'm not really sure how to fix this problem. I am very tech savvie, I solve things like this all the time but this one is stumping me.

I have another OS on another drive (from which I am posting this btw) and it always functions properly, so I think I can rule out hardware problems.

Problem is occurring on Windows 8.1 Pro x64

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft(R) Windows(R) Server 2003 Enterprise x64 Edition, Service Pack 2, 64 bit
Processor: Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz, EM64T Family 6 Model 42 Stepping 7
Processor Count: 4
RAM: 6113 Mb
Graphics Card: NVIDIA GeForce GTS 250, 1024 Mb
Hard Drives: C: Total - 238472 MB, Free - 127975 MB; N: Total - 305243 MB, Free - 143976 MB;
Motherboard: Intel Corporation, DH67CL
Antivirus: None