I couldn't pass up Newegg's X850 XT for $90 after MIR, so there have been some changes. This new vidcard smokes the 9800Pro (duh!), but the stock cooling unit is absurdly loud. The fan emits an annoying bearing growl regardless of RPM, and it took a full 5 hours before I couldn't handle any more. I'm sure someone here can relate...
No one ever bought the Maze4 GPU block I was supposed to sell for a friend, so I decided to watercool the GPU. Because the GPU block and my DDC have 3/8" barbs, I changed the CPU block's inlet to 3/8". The 7/16" tubing from CPU to rad and back to pump was not changed, so the conversion was pretty quick. (Note that I would change everything to 3/8" but that would require cutting the barbs from my heatercore...) The not-quite-final result looks like:
See the hi-res pics here
As I finished bleeding the system, the pump seemed louder than the last time I had the case open. I sandwiched the DDC in foam and reconnected it to the Sunbeam Rheobus, both of which help. Reducing the pump voltage to ~9V makes the greatest difference in noise level by removing the "edge" from the sound, and it does not affect temperatures very much.
Too much changed for valid comparisons of temperatures, and both fans still run at ~5V. Under normal gaming loads, the CPU and GPU both report about 50C in a 21C ambient, and I have no complaints about stability. One nice feature is that the fan speeds never change (at least not audibly), so the system's noise level is constant except for HD seeks.
Having the CPU and GPU in the loop really allows watercooling to shine. Both chips receive adequate cooling from a quiet 120, which ventilates the case as well! While adding the GPU block did increase CPU temperatures about 5-10C, the system's noise level actually decreased
thanks to the removal of the VGA Silencer. Achieving this with aircooling would be very challenging, though having no pump would allow slightly higher fan speeds at the same noise.
There's still room for improvement, of course, but this system keeps getting better and better. A lot of the credit belongs to the water.