Testing and Results
Testing was done with the setup you saw in the previous images. The loop consists of a Swiftech MCR 320, a Swiftech MCP 655 with EK top, a Bitspower POM80 reservoir and some 3/8" white tubing. I mounted it all to a board and covered the radiator with six, Lian Li LI121225BL-4 fans. They were used due to their near silent operation at 60CFM production levels. All testing was done at night so I could allow for a 25 degree Celsius, ambient temperature. I then applied MSI afterburner for clocking and fan control, and used the accompanying Kombustor to load the GPU's for results. This test usually maxes the temperatures quickly, but I allowed for ten minute runs to make sure I hit peak levels.
Out of the box with stock clocks of 625MHz core, 850MHz memory and 1250MHz on the shaders, and a core voltage of 0.950V, we get temperatures of 55 degrees on the coolest idling card, and at load they both settled out at 91 degrees. Another thing to keep an eye on is the PCB temperature. With these settings the PCB loaded at 65 degrees.
Using a tool like AfterBurner gives you the opportunity to change the fan profile to aid in the cooling at the expense of quite a bit of noise. Changing the slope to start at 0% fan speed with 0 degrees on the core, and ending at 100% fan speed at 80 degrees, this is what I got for the effort. Idling the 470 saw 51 degrees at idle and the hottest card only hit 78 degrees at load. The PCB temperature also dropped eight degrees with the fan increase.
Here is where the image of a ten minute run with an overclock of 795/1000/1590 should have been, but at 108 degrees the GPU's went into recovery mode and shut the test down. All I can say is that it failed and I moved on.
With my setting the fans curve, I was able to run not only this bench, but was able to keep them running games like Dirt 2 with no problems. Under Kombustors load, I saw the one card hit 101 degrees, but it was still running. Idling at 54 degrees was no surprise, but when you add the voltage control to the maximum level, you can see it really brings on the heat.
Once the loop was completely installed and bled free of air, I was surprised to see the results. A measily 34 degrees was where the cards idled, and even at load with the stock clocks I just touched 50 degrees.
Fully overclocked and with maximum voltage, the DD-GTX 470 block handles its business. 32 degrees idle temperatures, a full load temperature of 55 degrees, and even the PCB stays cool at a measily 39 degrees. I can't explain the difference in the idle temps other than it must have gotten a touch cooler between tests.
Here we can see all the idle temperatures side by side.
Again, a much more easily discernable load temperature chart. Once grouped like this, all I can say is WoW!