Today I looted an 80mm ADDA Sleeve Bearing Fan from a dead PSU, and hung it from the heatpipes near the back of the case (VGA output end) blowing inwards - not extracting at about a 45 degree angle. I already had 4 open slots there, so it is getting cool fresh air and blowing it along the fins, I rigged the fan to run @ 5v at work, and tested its startup ability - it was fine. It seems rather quiet at 12v, and quieter and smooth at 5v - this is not easy to tell as my work place is far from quiet, and it is currently too noisy at home to tell how quiet this really is......
Anyway, the interesting part is to see just how much (little) airflow the 4850 needs with an S1 to keep cool. Having had the PC on for 20 minutes with the graphics card doing nothing but displaying the SPCR webpage whilst runing at its default idle clocks of 500/933 the temp has risen 1C to a lowly 39C.
I am going to run ATITool to see via the graph the highest temp the card reaches whilst playing Company Of Heroes with everything maxxed out @ 1920x1200x32bit.
EDIT: ATI Tool does not want to run, it just eats half of my clock cycles and thats it, I will just have to flick over quickly to the CCC to see the numbers. After installing ATI Tool and it not working I rebooted, and re-tried it - by this time the GPU had hit 40C.
I will post back later with my findings, but I suspect that a single 80mm fan @ 5v on the S1 will keep the temps well within limits at minimal/no noise level. This I hope will prove/disprove that the 4850 can be cooled passively with the S1 given enough overall case airflow and the right airpath (Nick's) or a lower airflow system (Mine) cooled with very few direct CFM. We can then extrapolate the kind of airflow needed for people using the 4870 with the S1 cooler.
After about an hour, the core temp is 53C
The simple answer is that you wont need a lot of airflow to keep the 4850 cool with an S1. According to SPCR's re-tested (with more accurate results in purple) fans my fan @ 5v will output about 5-6 CFM. In a way it hardly seems worth the effort as the airflow is so small, but the results speak for themselves you really dont need a lot at all.
My results land inbetween Hardware Canucks results with the S1 running fanless and with the S1 with the turbo module installed.
http://www.hardwarecanucks.com/forum/ha ... ew-24.html