It was well worth the bother, and now I'm getting very good temps.
The Define R4 usually doesnt have any support for a 280mm radiator, but it's very easy to 'add' support.
- Put both of NZXT's included fans in to the fan bracket at the front of the case, and push them up so they're as far up in the bracket as possible (the top fan's 2 bottom screw holes should line up with the bracket, and everything else won't)
- Start drilling! I suggest using a 3'5 bit, but a 4 or 4'5 bit will work too (keep in mind that if you use a 4'5 bit, you may need to add washers. Use the fan's screw holes as a guide for where to drill. In the top of the bracket, there are little nubs to hold the fans in place. Use some pliers and snap them off to make it much easier to drill through (for these two holes you may need to drill from the other side.
- Now, that your holes are drilled, you need to find a place to put the hard drive tray. I don't have many hard drives, so I completely took out the top part of the hard drive tray, and then unscrewed the bottom part. You will notice similar holes slightly left of the usual holes. If you move it left, you will be able to put 3 fans on your radiator (2 push 1 pull). Your other option is to completely discard both hard drive trays, and use the 5.25" and 2.5" mounts (behind the motherboard) in the case instead, to allow for full push pull on the radiator (I tried both, and the difference between 3 and 4 fans in terms of temps is very minute). In order to fit the radiator in there, you're going to need to remove the plastic rails in the hard drive tray area (that allow part of it to slide on and slide off) this is very easy and the top screws can be found in the bottom 5.25" bay, and the bottom screws can be found on in the lower part of the hard drive tray (don't bother removing the bottom ones if you're going to completely get rid of the bottom HDD tray.
- Now that you've sorted out the hard drive tray issue, It's time to mount the radiator (you will install the CPU block after this). To actually fit the radiator in, I suggest you place all of the NZXT included long screws in the bracket, and put it in to the front (as you hear the click). Then, you will want to fit the radiator through the case, and hold it up. It's a bit tricky, but the screws are long enough to hold on to the radiator. I suggest you don't screw too far in, as you may damage the radiator fins (I almost punctured mine). Once it is screwed in, install the CPU block (I shouldn't have to explain how to do this), then plug everything and it should be good to go!
oh and sorry for the shitty pictures. My room has bad lighting and I don't have a lens for my 600D
if you have any questions, leave a comment. If I can't get back to you, pm me on reddit /u/Chozenus