On some mobo's where the clip is facing the top of the case.. making it near impossible to get the HSF on without removing the mobo. However, on my EPoX 8K5a2+, it has it where the clip is facing the front bezel, making it ALOT easier to install it without removing the mobo. If I do leave the mobo in, I remove ram, HDD cage and vid card.. just to be sure.