(THOUGHT I'D CUT N PASTE THIS INFO FROM THE GRAPHICS CARD SECTION FOR PEOPLE TO BE AWARE OF)
If you own a Gigabyte P67A-UD7-B3 be very careful when screwing down this heatsink onto this motherboard or any heatsink that uses that "X" clamp thing to attach it, as this motherboard channels 4 of the memory tracks from the dimm slots to to cpu socket directly under one of the holes you screw the cpu heatsink into, in my case after installing/removing the heatsink a couple of times for cleaning it caused the insulation to to be stripped from the surface causing three of these tracks to get shorted by the "X" clamp bolted onto them. My solution was to make 4 plastic shims to go under each leg of the heatsink so that there can be no further contact between metal and the motherboard surface. Why oh why do motherboard makers continue to channel circuit lines close to or directly under screw entry points - it's just asking for trouble, I had that problem with Abit in the past, motherboards that wont boot simply because you screwed them into place and shorted them out in the process because the screw has stripped the surface of a circuit track and is now short circuiting that track directly into the case. There is an abundance of room to place these tracks so come on Gigabyte lets think a little before designing these boards in future - steer well clear of the cpu heatsink mounting holes when laying circuit tracks....
UPDATE :- This issue actually affects both the lower 2 mounting holes so be careful mounting large heatsinks with the X clamp too tightly
I personally fashioned four pieces of plastic with holes in them to go under each of the heatsink mounts to prevent metal touching the motherboard surface, each piece around the size of a dime with a hole in the centre, as long as they're big enough to cover the circuit tracks it's ok.