Most boards are designed to take advantage of the air flow of stock coolers, so when people switch coolers, or go to water, they often find
The least expensive, effective, method of cooling that AMD 770 chipset would be to pop off that blue Gigabyte plate (it's a piece of aluminum attached with double sided tape), and then attach a 40mm fan to the heatsink. You'd probably want to pull the heatsink off and replace the thermal compound while you are at it. A 40mm fan can be attached any number of ways, from wire, to high temp hot glue (my favored method).
If you want to spend slightly less effort and a bit more money, grab an Enzotech CNB-R1 or some equivalent chipset heatsink instead (measure the distance between those mounting holes first.
The MOSFETs to the left of the CPU should definitely be sinked if you are using an X6. Some full size copper BGA sinks (again I recommend Enzotech, specifically their BRM-C1s, but others can certainly work) on them should do the trick. Getting air over them would really help as well. Also, if you have any way to get some air moving across the underside of the motherboard, that would likely help at least as much.
Actually, is your case wide enough for you to move the H50's radiator to the side panel and have it blow down at the board? If you can do this, you probably wouldn't need to add anything (though putting ram sinks on the mosfets would still be a good idea). This would make it tricky to remove that side panel though. Still, moving the radiator to another position and using it as an intake could move some air over the board, and get the radiator itself away from the mosfet area.
