Cooling Efficiency

Now let’s check out the cooling efficiency of Accelero XTREME 4870X2. First we will look at both testing participants with fans in automatic mode:

The first thing that we notice is that the temperatures of both graphics processors are the same when cooled by Accelero XTREME 4870X2, while in case of a reference cooler this difference reaches 23°C! This is common for Radeon HD 4870 X2 coolers, because the GPU heatsinks are installed one after another along the direction of the airflow coming from the graphics card fans. As a result, the second GPU heatsink is cooled with already hot air coming off the first GPU heatsink that is why its temperature is way higher. Accelero XTREME 4870X2 doesn’t have this issue, so we see no difference in GPU temperatures, which provides the new cooler with a 20-degree advantage over the competitor.

Three next diodes - GPU memory IO, GPU display IO and Ambient – show almost the same temperatures under both cooling systems. However, the temperature readings taken off the three VRM diodes are quite different, and not in favor of Accelero XTREME 4870X2. Radeon HD 4870 X2 reference cooler cools VRM 18°C better than Accelero XTREME 4870X2, but there are two things to take into account. First, 118°C is quite normal for the VRM of Radeon HD 4870 and similar graphics solutions and no one is scared of this temperature. Second, look at the fans rotation speeds that were used in automatic mode: Accelero’s fans didn’t even move when the temperature increased continuing to run at almost minimal speed of 1010 RPM, while the turbine on Radeon HD 4870 X2 sped up from 1400 to 3090 RPM. Now go back to the acoustics readings chart. I don’t think I need to tell you anything anymore :)

The next step (and a pretty logical one) will be to check the graphics card temperature in quiet cooler mode. For this purpose we manually set the fan speed on Accelero XTREME 4870X2 to the minimum of 980 RPM or 26%). The reference Radeon HD 4870 X2 cooler was working in a bit more favorable conditions with its fan rotating at 2290 RPM (35%). Here are the results:

Accelero XTREME 4870X2 at minimal fan rotation speed allowed the GPU temperature to increase by only 1°C compared with the temperature in automatic fan rotation speed mode. All other temperatures remained where they were. However, the reference cooler was nearly dying under the thermal pressure from the powerful graphics accelerator, because only a few minutes into the tests the temperatures rose to critical values and the graphics card thermal protection system started to kick in speeding up the fan to the maximum (as you can clearly see from the typical upsurges on the monitoring chart). In other words, if the reference cooler failed this test even in moderate acoustic mode, then what can we possibly say about the quiet mode?

Now let’s check out the results at maximum fan rotation speeds:

Since Radeon HD 4870/4870 X2 (and later HD 4890) came out, we have known that their cooling systems were extremely efficient at maximum fan rotation speed and it was very hard to find a worthy alternative to them. However, the today’s hero, Arctic Cooling Accelero XTREME 4870X2, leaves absolutely no chance to this dual-GPU graphics card cooler having yielded non-critically only in one reading (VRM diode). It doesn’t make any sense to compare the noise levels of the two coolers in this test mode: everything is absolutely clear.

To make the results a little more illustrative we summed everything up in a single diagram where we also added the results of Accelero XTREME 4870X2 at average fan rotation speed (1480 RPM). The stricken out numbers indicate the readings taken off the reference Radeon HD 4870 X2 when the test has to be manually terminated:

In my opinion, the most impressive group of results is the first one, where we see the temperature of the hottest GPU of the graphics card. It shows that Accelero XTREME 4870X2 in quiet fan mode cools the graphics processors just as well as the reference cooler at its maximum fan rotation speed. And it is simply impossible to compare the coolers efficiency at the same level of noise, because even at the moderate speed of 2290 RPM the reference cooler couldn’t cope with its task and the card got overheated. This way, Arctic Cooling did keep its word, because its new solution does in fact provide a 50-degree advantage over the graphics card stock cooler. Excellent result!

As for the temperature of other graphics card components, we are a little confused with the VRM readings. Looks like the aluminum heatsinks are not enough to ensure the same cooling efficiency as provided by the reference Radeon HD 4870 X2 cooler. Nevertheless, the difference is not as dramatic as what we saw by GeForce GTX 260. Moreover, these temperatures are pretty common for the VRM of Radeon HD 4870/4890/4870 X2 graphics cards and shouldn’t be considered something out of the ordinary.

And what do we see in FurMark? Here are the results:

Arctic Cooling solution proved more efficient also under higher operational load. Too bad that replacing the graphics card cooler and leveling out the GPU temperatures didn’t have any effect on the card’s overclocking potential: we managed to go only as far as 820/3840 MHz end frequency with both cooling solutions. The temperatures of the overclocked graphics card equipped with Accelero XTREME 4870X2 increased only by 2-3°C on each diode.

And the last thing that we should pay attention to in our today’s review. The thing is that the reference Radeon HD 4870 X2 cooler boasts one advantage: it ousts warm air outside the system case, while the new Accelero XTREME 4870X2 barely does it at all (only part of the airflow from the first fan leaves the system through the grid in the retention bracket). In other words, most of the hot air remains inside the system case. Therefore, we have one logical question: how badly will it affect the CPU thermals? To answer this question we used a new Resident Evil 5 benchmark that runs for about 10 minutes and loads not only the graphics card but also the all Core i7 cores. We launched this test in 1920x1200 resolution with enabled full-screen antialiasing 8x in order to increase the video load (the average fps rate was less than 50). We used RealTemp utility to monitor the CPU temperature. The graphics cards coolers worked in automatic mode. Let’s take a look at the obtained results:

True, the peak CPU temperature turned out 2°C higher when the graphics card was equipped with Accelero XTREME 4870X2 cooler. In my opinion this is very small price for the considerably lower graphics card temperatures and incomparably better acoustics. At the same time, it is important to keep in mind that we ran all tests in a well ventilated system case and in other system cases this difference may be more dramatic. However, I doubt that anyone will decide to install Arctic Cooling Accelero XTREME 4870X2 into cluttered Chinese mid-towers…