Frankly I was shocked too about temps drop.

But remember that even if S1 is fanless I have that middle inner fan who blows on it and on PCB back and SpeedFan controls it linked by GPU temp. Now it's on 600 RPM, but it seems to be enough.
I'm not an OC-er but I tried some OC on CPU/GPU. Now I have more numbers on 3DMark and Crysis.
Pentagram ramsinks are cheap and they're doing their job. I have another set on my 7900GS and it was OK. And you have 3 colours to pick: red, blue or black.