I dont think your missing much, my ram has a sweet spot @tras 24 with both kits combined i have a handicap but you should most likey hit 1600 with those gskills, my board likes under 1.60v (with both kits)

on another note I havent tried the new bios 3.5 I believe, using only my ocz 2000 kit yet but when I have time Im going to see what they will do alone.

I think the trick with this board is to keep qpi under 1.70 and DISABLE AUTO DISABLE DRAM/PCI setting in bios and lock @37.3.
There is more bandwith to be had and Im wanting more I will post screen when mine are fully stable @1500ish with both my ocz and kingston kits. I did pull 666-24 out of both kits @585 ish for 24-7.