Just need to take your time to do a good job. I don't remember exactly if i use existing holes for top fan and just cut xtra space behind or rehole. Check clearance between mb and top of your case before cause mine fit by 1/16''. I use h100 screw and they were a little short but just enough. You wil need to fing something to cover rough edge.
NVIDIA [GTX 560/560 Ti] OC Club CPU: I5 2500K O.C. 4.7 Ghz 1.38v MB: ASUS Sabertooth P67 RAM: CORSAIR XMS3 1600 Mhz cas9 GPU: SLI ASUS GTX 560 Ti 920/1840/2200 COOLER: CORSAIR H100 SSD: OCZ Agility 3 120 Gb HDD: 2x WD 750 Gb sata 3 raid0 PS:CORSAIR TX750 MONITOR: ASUS VE208 + ASUS VG236 CASE: CM Storm Scout black