^^ decent will be around ~ 1cm to 2.5cm depending on the PCB and cooler layout (the MSi Twin Frozr's are notorious for this). Hope this helps.
HAF 912 / 922 ( and most other cabinets) place their disks parallel to the graphics card stacked horizontally, whilst the NZXT Tempest EVO has a drive cage with vertical orientation perpendicular to the graphics card orientation, so this can obstruct removal and placing of hard-disks while the graphic card is very long, that is okay by me as I don't tinker around with my hard-disks but to some folk this can be a deal-breaker.
So that is why I leave choice to you Sire.
The clearance of most Cooler Master cabinets on the CPU corner is a bit too stuffy for my linking, the CPU clearing in the NZXT Tempest EVO is better than the Cooler Master eLite 430, my Cooler Master Storm Scout as well as Cooler Master 690 II.