Upgrade from 8Gb to 16 Gb

[Blessed again]

I would like to upgrade from 8gb to 16 gb memory.
I have an Asus Maximus iv extreme-z, an i7-3770K CPU and 2 sticks of F3-12800 CL9D-8 GBxl. I would like to know if adding 2 sticks of F3-12800 CL9D-8GBRL would work well. i found a bargain on Newegg but would rather spend more if it would eliminate problems.
If these will not work what do you recommend?
Win. 7 ultimate, Nividia GTX 560ti, 1-Corsair 125Gb SSD, 1-Intel-180Gb SSD, 1-2 TB Black HD, !-1TB HD, EK-Supreme HF Cooling, 3-Fan Radiator, 1200 Watt Corsair PS

[Tradesman]

Anytime you mix sets of DRAM it can be problematic, normally at 1600 it would prob be fairly easy if using the same model, but here you are looking to take current Ripjaws X sticks and pairing them with the regular Ripjaws. I would imagine it would be fairly easy, prob slight adjustments to DRAM and MC voltages....and possibly an adjustment to the tRFC in the advanced timings. If you wish, I'm fairly certain we can get them to play nice....but if you want the easier route, that would have advantages....to that end I'd suggest a 2x8GB set of DRAM, leaving 2 slots open for future expansion as well as less stress on the MC (memory controller) with only 2 sticks vs 4 in a 4x4GB setup. Either way, if help is needed, we'll be here

[Britton30]

I would even go to 2133 or 2400 RAM too, I think it would work well with that system. You would have to make UEFI adjustments though.
A 16GB kit is quite reasonable in price too.