I have the PC-Q08 running for a couple of weeks now. Sound and heat production is OKE at idle, but sounds like an airplane while gaming

The problem I hope some of you guys can help me with is the aftermarket cooling question. I understand that the normal choice (Shuriken big2) will interfere with the PCI-E slot which I use with a HD7870.
My setup is; Asus P8H77-I, Intel I5-3450, 128SSD and Asus HD7870 DirectCUII.
Now I am thinking of replacing the CPU cooler with the Noctua NH-L9i, which I think is pretty expensive, but receives a very good review here:
http://www.rwlabs.com/article.php?cat=&id=744
Am I missing good alternatives here?
The most noise comes from the HD7870. The directCUII cooler is silent at idle, but when you start gaming it will surprise you with vacuumcleaner like noises. The space from the bottom to the HD7870 is limited though, so I can imagine that not every cooler will fit, or will work optimal due to the small space between the "floor" and the fan.
What are your experiences? Tips and advices are more than welcome
