Cooling Efficiency Tests
As I have already mentioned above, the coolers are listed in ascending order according to their noise measurements, i.e. in the same order as on the previous diagram (at 1m distance). So, the coolers at the bottom of the chart have the least comfortable acoustic performance. The first diagram will discuss graphics processor temperature (GPU temp) and the temperature of the hottest voltage regulator component of the three (VRM temp):
The next diagram shows the data for three more sensors: "Display IO temp", "Shader core temp" and "Memory IO temp". However, since they are pretty similar to the first two we are going to discuss only “GPU temp” and “VRM temp”.
So, all alternative cooling system work well for the GPU. Scythe Musashi and Arctic Cooling Accelero Twin Turbo work best of all in quiet mode with the fans at their lowest speed as well as at maximum fan rotation speed with moderate noise level. However, the reference Radeon HD 4870 solution cannot ensure proper GPU cooling at minimal fan rotation speed. If you speed its fans up to ~2400 RPM the GPU temperature goes down significantly, but it is still behind the leaders. The third cooler, Titan Twin Turbo, is not that far behind Scythe and Arctic cooling in terms of efficiency, but, loses dramatically from the acoustic prospective.
Everything could have been really great, if it hadn’t been for the VRM components cooling. Look at the second group of results on the first diagram. It appears that none of the alternative solutions can cool these components properly in quiet mode. This is why we only tested the coolers on a graphics cards working at its nominal frequencies and didn’t overclock it: even when we increased the GPU frequency only to 800MHz the card would hang during the test cycle, which didn’t occur with a reference cooler. Even the aluminum heatsinks on these components didn’t help improve the card’s overclocking potential, unfortunately. I believe that cooling solution makers should really consider offering larger aluminum or even copper heatsinks with proper retention for these components on graphics cards like Radeon HD 4870.
Note how well the reference Radeon HD 4870 solution cools VRM component even at ~2400 RPM. It is very simple: since these components are located right beneath the fan, the greater the airflow – the lower their temperature. But if we have to decide on one of the alternative cooling solutions, then Scythe Musashi and Arctic Cooling Accelero Twin Turbo again will be the best call. The airflow from the fans of a short Titan Twin Turbo doesn’t cover the entire VRM zone of the PCB, so these components may run pretty hot.