a build your own setup will cool MUCH better than the pre-builts.
The only thing is is that it will require some elbow grease to get the case setup how you like it, it will take research on what blocks you can use (HK Supreme allows LED's in the block), radiators, and pumps.
They also need about 24-48 hours to test for leaks. BUT they are much easier to clean than the prebuilt options.
And as for the above post, go over to xtremesystems and see why they wc

its mainly for the aesthetics now and the showmanship. The temps are a bonus but really unless you are overclocking to extremes air cooling options have come a long way in the last 10 years as well as processors, making it easier to achieve high overclocks with minimal temp differentials.