Too many variables.....
What kind of RAM cooling
How mounting megahalems (blowing up / blowing to rear)
I can tell you that the Megashadow fits on an R2E w/ Mushkin Redline modules with Ascent coolers. RAM is in blue slots so one closest to GS is empty.
BTW, you'll want the 1200 rpm fans as prolima recommends 800-1200. The also recommend having fans blow to rear, not to top. I have just been told by Asus tho that the reason that my HS fans on the Megashadow are not adjusting speed according to load is because the fans I am using are not PWM.
I have them on fan controller now which requires pressing F1 on bootup to get rid of the "No CPU fan" message. Eventually I will get around to replacing them with PWM fans.....prolly going to get these:
Enermax Cluster are 53 cfm, @ 500-1200 rpm and 8-14 dBAhttp://www.frozencpu.com/products/7489/fan-437/Enermax_Cluster_120mm_x_25mm_LED_PWM_Fan_w_Twister_Bearing_Technology_-_White_UC-CL12.html?tl=g36c365s936
S-Flex SFF21E are 49 cfm, @ 1200 rpm and 20.1 dBAhttp://www.frozencpu.com/products/2505/fan-205/Scythe_S-FLEX_SFF21E_120_x_120_x_25_mm_Fan_w_S-FDB_Bearing.html?tl=g36c15s60