I just recently switched from an Antec 900 to an NZXT Phantom, and I am slightly disappointed. First off, the temps in the antec 900 with poor cable management was 10 degrees cooler than the temps are now in the phantom with well managed cables. The max temp I saw from my 560 ti in the Antec was 63 celcius and CPU was 51 Max, now the 560 stays about 68-70 constant and CPU hits 55 while playing rift.
A few of the differences between cases I have tried to think of was #1, My PSU was facing up in my Antec 900 as opposed to facing down in the Phantom because of the vents and dust filter on the bottom. #2 Two 120 MM fans from the Antec pulling in cold air as oppose to the two 120 mm side fans pulling in air and blowing it straight across to the other mesh vent. I've also come to find out that if I put a 120 or 140mm fan in the front of the case as intake, the HDD Cage is basically blocking air to get through.
I've searched continuously online for solutions and I can't really find any mods or better fans to put in the case to achieve the best cooling without switching to water cooling. Does anyone have any suggestions on what fans would be best for the case?