Gigabyte makes some quality overclocking gear. I have managed to take a dual-core i5 up to 5.5GHz using a mini-ITX Gigabyte board, so it comes as no surprise to me that HiCookie, Gigabyte's staff overclocker, managed to take some G-SKILL 2800MHz RAM up to 3100MHz using one of their Z77X-UD5H motherboards.
Sure, it took some extreme cooling, but by using what appears to be liquid nitrogen, he managed some impressive clocks, even with all four memory slots populated. The system used included the Gigabyte Z77X-UD5H with BIOS F8c and 4 x 4GB G-SKILL 2800MHz RAM. Often when overclocking, it is easier to use the minimum channels of memory to lessen the load on the memory controller, so having all four slots populated is even cooler!
HiCookie has managed some other impressive feats in the past, and I'm sure he will manage more impressive feats in the future. Keep an eye on Gigabyte as they are doing some cool stuff. Something about creating the lightest notebook or something like that. They should also have some boards with Thunderbolt in the pipeline as everyone else is releasing them.