|MSI R6870 Radeon HD 6870 Video Card|
|Reviews - Featured Reviews: Video Cards|
|Written by Bruce Normann|
|Friday, 05 November 2010|
Page 15 of 18
MSI R6870 Temperatures
It's hard to know exactly when the first video card got overclocked, and by whom. What we do know is that it's hard to imagine a computer enthusiast or gamer today that doesn't overclock their hardware. Of course, not every video card has the head room. Some products run so hot that they can't suffer any higher temperatures than they generate straight from the factory. This is why we measure the operating temperature of the video card products we test.
To begin testing, I use GPU-Z to measure the temperature at idle as reported by the GPU. Next I use FurMark 1.8.2 to generate maximum thermal load and record GPU temperatures at high-power 3D mode. The ambient room temperature remained stable at 23C throughout testing. I was lucky to have some nice weather during testing, since my testing is done in an upstairs room that doesn't get as much of the central A/C as I would like. I do have a ton of airflow into the video card section of my benchmarking case, with a 200mm side fan blowing directly inward, so that helps alleviate any high ambient temps.
The MSI R6870 video card recorded 36C in idle mode, and increased to 72C after 30 minutes of stability testing in full 3D mode, at 1920x1200 resolution, and the maximum MSAA setting of 8X. With the fan set on Automatic, the speed only rose to 31% under full load. That was such a low fan speed and a high temperature, that I immediately did a run with manual fan control and 100% fan speed. I was rewarded by the noise of a hair dryer and a greatly reduced load temperature of 54C.
72C is not a very good result for temperature stress testing, in my opinion. I've become used to seeing video card manufacturers keeping the fan speeds low, especially with the type of radial blower wheel that this reference design uses. In this case, the fan controller barely ramped up from the idle speed of 21% to the 31% mark when running at full load on auto. Obviously, AMD is trying to minimize normal operating noise while retaining a lot of headroom in case things go south inside the PC case. There is definitely some thermal benefit to running the fan harder, as you can see from the 100% fan results above, but the noise is overbearing at full tilt. I expect a lot of users will make use of custom software profiles to control the fan on their HD6870 reference design.
For me, this type of fan noise is more irritating than what an axial fan produces, so I understand why AMD is trying to keep the fan speed down as low as possible. I prefer a video card that pushes all the heated air out the back of the case, and that almost forces the use of the radial blower, so I guess I shouldn't be surprised by the noise performance of this cooling design.
Load temps got up to 69C when running continuous gaming benchmarks with automatic fan speeds, ramping up to 30% with the most challenging titles. This is closer to stress-test-maximum than any other card I've tested, which tells me that this is the operating temperature range that AMD has selected for this GPU. It's higher than I like to see, and I don't think it bodes well for overclocking, but ultimately AMD gets to pick the operating point. I think this also explains why they used such a thick block of copper on the GPU heatsink. That gives the cooling system the ability to absorb and dampen out temperature spikes far better than a design that uses a thin layer of copper to transfer the heat to the heatpipes and aluminum fins.
FurMark is an OpenGL benchmark that heavily stresses and overheats the graphics card with fur rendering. The benchmark offers several options allowing the user to tweak the rendering: fullscreen / windowed mode, MSAA selection, window size, duration. The benchmark also includes a GPU Burner mode (stability test). FurMark requires an OpenGL 2.0 compliant graphics card with lot of GPU power!
FurMark does do two things extremely well: drive the thermal output of any graphics processor higher than any other application or video game, and it does so with consistency every time. While FurMark is not a true benchmark tool for comparing different video cards, it still works well to compare one product against itself using different drivers or clock speeds, or testing the stability of a GPU, as it raises the temperatures higher than any program. But in the end, it's a rather limited tool.
In our next section, we discuss electrical power consumption and learn how well (or poorly) each video card will impact your utility bill...