FYI.
I got my two NV Silencer 5 Rev. 3's from UPS and installed them last night.
They fit - even with the X-Fi soundcard sitting in between!
And they help the temps a lot. The following temps are under video load from running 3dMark05 multiple times in a row. I have two BFG 7800GT OCs. And am running an X2 4400+ at Auto everything in bios and with the stock HS. The case has pretty good airflow but I'm running all Nexus 80mm fans (two rear exhaust, one lower front intake and a side panel intake blowing on the PCI slots).
Before:
MB-47
CPU-47
After:
MB-40
CPU-44
I don't have my notes with the GPU temps right now (I'll post them later along with picts of the rather crowded case). But IIRC, the GPU temps went down around 5 degrees (more on the lower card than on the top card).
And the better thing is that all the temps remain the same even when I oc'd the cards - right now just at "optimal" settings of about 445 and 1.8. Before oc'ing the cards really jacked all the temps up.
Two problems with the install though:
1. The fan on the upper card initially didn't turn.
After looking a bit more closely, I realized that the X-Fi was touching the hump on top of the fan (which faces down in the case). Luckily I was able to cut a little piece of rubber gasket I had lying around and jam it between the X-Fi and the clear plastic edge around the fan. That gives it enough clearance to now turn freely.
2. But even with that clearance, the X-Fi is still long enough that the last inch and half covers the air intake area on the upper NV Silencer. The result seems to be somewhat higher temps (about 5+ more than the lower card). But the temps are still lower than with the stock cooler so I'm not that worried about it.
Oh yeah and the screws on the stock cooler on one of the video cards were REALLY tight. I almost stripped them trying to get them off, but in the end it worked.
So all in all I'm happy with the addition.