Megahalems cooler will fit. The problem is RAM under fan.
40mm = RAM+3mm = socket
43mm = motherboard to top of RAM
120mm = fan+43mm = RAM & socket
163mm = motherboard to top of fan
163mm = CPU clearance in case+ 8mm = motherboard to top of CPU
171mm = motherboard to case side cover
` ` 8mm = clearance
Keep in mind that the testing procedure used my most reviews is seriously flawed. The use of room ambient temperature is not an accurate baseline for temperature of air going into cooler. Check the temperature of your room, then check the temperature near your desk / computer. I'm betting a cup of coffee it is a couple degrees warmer .. and this will be cooler than the air inside of case, especially under load. Air going into cooler under heavy load is often 8-12c warmer than room. Switching to a different cooler changes airflow characteristics and therefore temperature .. and if the air going into cooler is 12c warmer, the CPU will be at least the same amount warmer.
Simply changing cooler fan speed usually changes cooler intake air temp .. as does adding a 2nd or 3rd fan.
This is why we see one review changing from push to push / pull getting 1-3c improvement and another getting 6-7c improvement. It's not the fan improving cooler, but the fan changing case airflow and cooler getting lower temperature air.
I often have a second cooler fan as rear exhaust plugged into same control as CPU cooler. This greatly helps exhaust the heated air coming out of cooler .. case exhaust fan is moving same amount of air as cooler fan .. all of air into cooler is exhausted out of case.
Example of how this works is Thermalright HR-22 and Macho Zero having a duct from cooler to rear exhaust with no fan on cooler, yet it performs as good or better than similar coolers with fans.
If you haven't read it, you might find the case cooling link in my sig interesting.