It could be crashing when it tries to switch between C-states. Does you BIOS have options for disabling certain C-states? Like C1E?
EDIT: Also, experiment with Load Line Calibration if your mobo allows. That is known to crash idle CPUs.
EDIT2: Also welcome to OCN! I hope you enjoy your time here
Unless you hate Radeons, go with R9 270 non-X, or R7 260X instead of 750Ti - cheaper and faster. And R9 270 non-X can easily and safely be OCed to 270X levels (it is the same exact chip, lower stock frequency).
My account is currently muted and can't add or be added as friend. It is a technical issue, not me being reported for inappropriate behavior I've contacted tech support, as soon as the issue is resolved, I'll add you Have fun playing!