The answer is, four 360 mm radiators without any modding. A big thank you goes out to Jim from CaseLabs for making this happen Its an awsome case!!! Check it out here: http://www.overclock.net/case-labs/ 2 in the top 1 in the bottom of the psu compartment. This will however only allow you to use 1 psu! And one in the bottom of the mainboard compartment. Putting a radiator in the bottom of the mainboard compartment will however kill 2, MAYBE 3 of your slots. Its a tight fit if it only takes two. You can however just leave it with 1 fan in the front. With all of this, you still have room for two hdd bays (8 harddrives, or for example 7 harddrives and two ssd´s etc. 2 ssd´s takes up what 1 drive does) and 4 5.25" bays if you take the front fans off. Maybe only two if you have full fans on. You can also just use only one hdd bay in the psu compartment, and then have 3 more 5.25" bays for aquaero epicness or likely in the motherboard compartment! Hope you could use it!