I recently built a new computer using a Gigabyte GA-EP45-UD3P motherboard. I used an Intel E8400 CPU for the board and when building the machine used the stock fan that came with the chip.
When installing the stock fan, it barely fit use to the heatsinks and in fact necessitated me removing one of the arms that were factory installed to hold the fan wires. Because of the placement of the heatsink being so close to the CPU, I want to ensure whichever heatsink/fan combo I purchase will fit the board.
I was looking at the ZALMAN CNPS9700, ZALMAN 9500A, or ARCTIC COOLING Freezer 7 Pro but am a bit concerned that which ever I chose will be too large for the board. I'm hoping someone who has used this motherboard before can recommend a fan that will fit and that will work great.
Here's a Freezer 7 on a DS5 (same board layout, I believe, as are most GBs...); I just clipped out the lower most 'cage bar':
and wired it thus:
I think I have a picture taken from the RAM side of the board; I'll try to root it out some time today - gotta deal with the snow first, we added about 4 inches to our 46 inch total of 'global warming' laying in the driveway...
I too have just built a new computer, with a Q9550 overclocked to 3.0Ghz. Its Thermal Spec says its fine up to 70'C, but I did away with the stock cooler and bought a Scythe Ninja 2, which has 3 heatpipes up all four sides as well as a 120mm fan for its side. This keeps my Q9550 at 22-23'C on idle which is fantastic, and 40'C after 15 mins of Prime95 on full.
Because of the fan's size, its also much quieter than the stock cooler.
To conclude, if this HSF keeps my overclocked 3.0Ghz quad core at those temps, it would be perfect for your E8400, and would give you plenty of overclocking potential.
Your board is also LGA775 Socket, and the Scythe has these fittings included.