The Zalman I tested was the CNPS 6500B-AlCu.
I doubt that either the Alpha 8942 or the Swiftech MXC4000-B would work well without a fan. However the more efficient the design the less airflow that is needed. Both these heatsinks should work well with a slow (practically noiseless) fan. The main advantage of both these HS's is that they can draw in air from all around the entire HS. A finned HS can only draw air from two sides.
I have now tested the 8942. At first I tried it with a 70mm x 15mm fan blowing down on the heatsink like Intel's HSF. In this configuration the CPU ran at 56 deg. C. This was much worse than the Intel HSF so I decided to follow the directions and install the fan blowing upwards away from the HS. In this configuration the CPU temps dropped to 44 deg. C and the case temp only 32 deg. C. All tests were done at full CPU load using Hot CPU Tester Pro with ambient air at 22-23 deg. C. I did not have the ATI 9700 Pro installed at the time so I can't really compare the numbers with my last test.
The fan up configuration works extremely well in this case. My theory is that with the fan blowing down, like in the Intel HSF, the CPU fan and the case fans are working against each other fighting for the same air to pull in. This could lead to cavitation and a reduction in airflow. With the CPU fan pointing up, the CPU fan is actually feeding the case fans with hot air to be expelled from the case. The cool air, down low in the case, is being drawn into the CPU HS keeping the CPU supplied with a constant source of cool air. It also helps promote linear airflow throughout the case. With the case fans mounted high in the rear of case, the hot air coming out of the CPU HSF is being expelled immediately keeping the case temps much lower. I am really excited about this new breakthrough in airflow for this case.
This first test was done with a 70x70x15mm fan running at 3300RPM. I ran a second test with a resistor that brought the speed down to 2000 RPM and the CPU ran at 48C with the case still at 32C. Case fans were being controlled by the new fan controller and ran about 1900 RPM.
I have ordered a Sanyo Denki 109P0812M701 80x80x15mm fan, 2000 RPM with sleeve bearings. I got the parts directly from Alpha. I think this fan will move even more air at lower RPM's. You can buy the whole combo here http://www.sidewindercomputers.com/alpalretbox.html
I will do some more tests with the Radeon 9700 installed after I get the new fan.