So... just to clarify, I can just use a 1600hz ram, and manually adjust TO 1600hz?
Yes if you are not overclocking your CPU much.
No if you are overclocking your CPU a lot, the RAM might go unstable.
Honestly i wouldnt buy G-skill though, there cheap for a reason.
Go for a reliable brand.KHX1600C9D3K2/8GX
But that, IMO is better, but you can get away with cosair, crucial, mushkin ect.
BTW the ASRock Company can't test EVERY DIMM on the market but if you want to play it safe, go crazy.
For Gskill i would get this,http://www.newegg.com/Product/Product.aspx?Item=N82E16820231416