People have tried all sorts of BIOS tweaks and it's helped some people, not others. If you stick a fan on the VRMs the problem goes away - or if you have rev 4, with its much improved heatsinks + heatpipe.
Gigabyte's tech support simply said to me about rev 3 that the board will always throttle the CPU if the mosfets get too hot with higher clocked processors, which is true of every board. They won't do an RMA replacement on rev 3 to get rev 4 unfortunately. It's not worth the effort or risk in my view, when you can get a similarly priced Asus board that has given nobody any problems.
I've got nothing against Gigabyte, I have two of their Intel Z87 boards and am happy with them.