Hi, I would suggest matching the fan to the heatsink size for best results. To an extent these stock video card heatsinks are "space limited" so to get the cooling surface area you have to pack the fins tighter. To get enough air through a tighter fin stack you need more pressure, which more-or-less means greater fan blade speed. The ends of the fan blades are going to be moving fastest flowing most air at greatest pressure. If the fan is massively oversize the high-speed tips will miss the heatsink leaving low-speed/pressure inner end of the blades over the heatsink.
Of course it's never that simple and maybe the extra surrounding flow is cooling other components or helps in some other way, anyway I wouldn't go mad with the fan size!

I'm a big fan of keeping replacement fans connect to original headers if they offered speed control. E.g. my GTX260 keeping PWM fans with modified fan curve could idle them at 25% / 625rpm and yet if the temp went over ~70°C the speed started to be increased independent of any software etc, safe and fool proof! Most of my PSU fan swaps connect replacememnt fan to original header too.

Regards, Seb

I can't really recommend anything yet, as I'm not sure how well my solution will work out.

I'm going to use the Scythe Kaze Master.

About the pressure, using fans with more tightly packed fins also works. Right now, I already have a couple of 500/700 RPM Noctua fans laying around (not meant for this kind of use at all) that I'll test first. If they are able to to the job properly, I'll keep them in, if not, I'll replace them with a couple of Noctua fans meant for CPU-coolers (more fins).

I have the space, so there's no reason not to use larger fans. I don't particularly agree with the theory of having to use small high-RPM fans to have sufficient pressure (unless someone proves me wrong with sources). After all, larger fans move more air in total, more and bigger fins means more fin real estate and more air moved. Even though some of the air might miss it, the amount of air pushed towards the cooler will be larger (with the same amount/size of fins), because the actual area over the cooler will be the same (if we ignore the fact that the "excess" air also helps).

I guess you could argue that good quality smaller fans that have the same surface area on the fins might perform better (make less sound) than a fan with a larger diameter, at the same RPM, but to be quite honest, I haven't got any experience with any 92 mm or 80 mm fans that perform excellently, so that would be a gamble for me in any case.

Update:

I just installed the two aforementioned Noctua fans a few minutes ago.

Let's just say I don't have to worry about noise any more. Right now, I can hear the low rumble from the city (and I don't really live in it). That's pretty damn good. I actually can't hear the computer over the noise in my studio monitors. If I turn them off, my fridge makes the most noise (in the far distance) (can't really do much about that now, though).

So, yeah, I'm running them on 700 RPM, and after some light usage, it seems they perform pretty much the same as the ones I took off, only they don't make enough sound to escape my case. I haven't tried running anything really taxing, but it's not like I'm going to use this computer for anything like that in any case.

They're probably not pushing enough air to game on, though. I would rather recommend fans made for cooling coolers for that, but I think 120 mm actually is a better fit (than 80 mm or 92 mm) for this particular cooler, as 2 x 120 mm is a pretty perfect fit on top of it.

I'm a happy camper. Finally I can get back to recording sound in this room again.

Congrats on finding the enjoyment that is quiet computing . I can sympathize with the monitor noise. I didn't know my monitor back home in Iceland was buzzing until I quieted my computer. Actually turned up the fan noise a bit to a gentle whoosh to drown out the monitor, since that was more annoying.

You don't have speed control of those fans? If you do you can just check on the heat after an hour of gaming and ramp them up a little bit if necessary.
But it's surprising how much cooling you can get with the right fans on the quiet speeds . You can also try some bench marking and see how the temps react.

I'm also working on quieting/cooling a GTX 570 (by EVGA). Several of you have talked about the Thermalright Shaman and Spitfire. I have questions related to both of these.

For the Shaman: I haven't been able to find anyone in North America that stocks it. I've gone through all the dealers listed on the Thermalright website, and for some reason none of them carry the Shaman. Can't find it on Ebay either. Have any of you found it?

For the Spitfire: according to my measurements, once installed with a fan the spitfire will sit right up against the side panel of my Antec Sonata IV, leaving to room to draw air. The Sonata is 8.1 inches wide, as are most of Antec's cases including the P183 and Solo II. Has anyone run into this problem?