Hello. I ordered a pair of these way back in 2012 (G.SKILL Ripjaws X Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-8GBXL - Newegg.com). They're still running great but I'm wanting to upgrade to 16GB of RAM. My question is can I just buy another set of these sticks and run them right next to my other two? Totaling 16GB? Or would that not be compatible.

My Motherboard: ASRock > Z77 Extreme4