Are these parts compatible with each other? this is my first time building a PC so I'm fairly new at it, but I'm relatively sure they're compatible, id just like some confirmation . Primary use will be for gaming.
Motherboard - Gigabyte GA-Z68X-UD3H-B3 Motherboard
CPU - Intel Core i5 2500K
RAM - G.Skill Ripjaws X F3-12800CL9Q-16GBXL (4x4GB) DDR3
Graphics Card - Sapphire Radeon HD6970 2GB
PSU - OCZ Fatal1ty Series 750W Modular
Hard Drive - Western Digital Caviar Black 1TB WD1002FAEX
Case - Lian Li Lancool First Knight PC-K63
Yeah, they're compatible. The only thing I would change is the HDD. The Samsung Spinpoint F3 1TB is quieter, cheaper, and has the same performance.
Also, 16GB of RAM is a lot. You may have reasons for it, but it is more than is necessary for most applications.
The PSU is not great. Here's the product brief: http://www.ocztechnology.com/res/manuals/OCZ750FTY-Fata...
In a 750W psu, 650W on the +12V rail is not very good. Maybe spend a little more on a better name like Corsair or Antec and think about the wattage. If you aren't planning on crossfiring in the future, 750W is a little much and if you are planning on crossfiring in the future, 750W is not quite enough.