Many of the larger aftermarket fans will block the #1 RAM socket so there is not enough height to seat the RAM stick. If you are going to use 2 RAM sticks, they go in #2 and #4 on the ASUS boards, so that's not a problem.
One solution is to use the Intel XTS1000H cooling fan, which is pretty decent, and won't obstruct the first RAM socket. Made for 1156 and 1155 CPUs. It's a heat sink, fan and fins unit but made to not overlie the RAM sockets.
Other nice solution is to use the Corsair H60 self contained liquid cooling unit, that has a square shaped pump that is about an inch high over the CPU, a replacement 120mm exhaust fan with PWM 4 wire control, and a radiator that fits just behind the fan. Made for the 1156 and 1155 CPU's, so your 3770K is good. No obstruction either and it's low profile and very quiet. Here is a link to a UTube video on how they are installed.