8gb of ram is plenty and if you want to you can always add more later.
As for the motherboard personally I'd go for Gigabyte G1-Sniper2 Motherboard [G1-SNIPER2] - $425.00 : PC Case Gear
this before I went for the Asus.
As for Ram I'm running G Skill ram atm..I should have gotten Ripjaws but I didnt lol...I'd go for Corsair over GSkill only if the latencies were tighter otherwise both are premium ram sticks.
Re overclocking ram: basically you will see no real world difference. For benchmarking it is, as always a matter of degrees and I have found Corsair will overclock better than Gskill. Ocz ram was the best for overclocking.It didn't void warranties it could be overvolted to buggery etc but as I said Ocz got out of ram and nowadays concentrate on SSD's.
If you buy GSkill get the Ripjaws and if Corsair get the Dominator. And both come with a aircooling fan clip on doover.If you going to play with latencies overclocking and overvolting them best to keep them cool.