Well, I have to say, thanks for all the interesting replies guys. I can definitely see now how bad a combination this case, and these cards are together.
However, last night, I performed a silly hack inside the case. I sellotaped a 120mm fan to sit directly across both 460s (facing down.) This dropped temperatures by 10c/5c on sep cards. This wasn't really enough (esp with the door closed.) So I removed both PCI back-panels from directly under each card to improve airflow. This has successfully dropped the temperature on both cards now by around 15c, so during gaming, they never breach 80c.
This is still slightly high, but shouldn't really cause any damage. Fortunately these cards have a 2 year warranty, so I'm either just going to wait until they both fry, or get myself a proper gaming case to transplant the gear into.
Fortunately though, the case is still pleasingly quiet, which is actually what I like most about the setup.. Until you start any kind of heavy game, but that doesn't matter when you're wearing heaphones
So yeah, top tip.
DON'T GET A NZXT HUSH CASE IF YOU'RE SETTING UP AN SLI RIG.
However, last night, I performed a silly hack inside the case. I sellotaped a 120mm fan to sit directly across both 460s (facing down.) This dropped temperatures by 10c/5c on sep cards. This wasn't really enough (esp with the door closed.) So I removed both PCI back-panels from directly under each card to improve airflow. This has successfully dropped the temperature on both cards now by around 15c, so during gaming, they never breach 80c.
This is still slightly high, but shouldn't really cause any damage. Fortunately these cards have a 2 year warranty, so I'm either just going to wait until they both fry, or get myself a proper gaming case to transplant the gear into.
Fortunately though, the case is still pleasingly quiet, which is actually what I like most about the setup.. Until you start any kind of heavy game, but that doesn't matter when you're wearing heaphones

So yeah, top tip.
DON'T GET A NZXT HUSH CASE IF YOU'RE SETTING UP AN SLI RIG.