Dual fan cooling
Without a doubt, the most notable difference between the ASUS EAH3870 X2 1GB TOP and AMDís own Radeon HD 3870 X2 board is the ASUS cardís unique cooling solution.
While AMDís reference cooling design relies on a mixture of conventional copper and aluminum heatsinks resting above the GPUs and powered by a single fan, the cooler on the ASUS EAH3870 X2 1GB TOP uses heat pipes. Resting directly above each R680 GPU is a copper plate and heatpipe. The heatpipes themselves are roughly four inches in length and are cooled by aluminum heatsinks which rests a quarter of an inch above and behind the GPUs. One heatsink/heatpipe combination is used per GPU, and each of these coolers has their own dedicated fan above them supplying cool air from within the case to each cooler.
With two fans the ASUS EAH3870 X2 1GB TOP is slightly louder than AMDís Radeon HD 3870 X2 board, but by no means would we consider either card anywhere close to being noisy or loud. They both run considerably quieter than graphics cards from a few years ago. Itís also important to note that due to the nature of ASUSí cooling design, hot air from the cooler isnít exhausted outside the case, this is another key difference between their cooler and AMDís.
We ran some temp tests between the AMD Radeon HD 3870 X2 and the ASUS EAH3870 X2 1GB TOP. In our testing, the ASUS EAH3870 X2 1GB TOP idled at 40 degrees Celsius whereas the AMD 3870 X2 card ran 45 degrees at idle. Under load the ASUS card was three degrees cooler Ė 61 degrees Celsius versus 64 degrees Ė keep in mind this was done with the ASUS card running at its standard TOP speeds, so the AMD board was running slightly slower.
There are a couple of oversights with AMDís cooling solution that we should mention though. For starters, the PLX chip that splits the PCIe lanes between both GPUs (16 per GPU) isnít actively cooled. On the stock AMD cooler, a thermal pad connects the PLX chip to the AMD cooler. Second, the memory modules on the underside of the card arenít cooled either. On the AMD reference design, an aluminum plate is used to cool the modules on the bottom of the card. Letís discuss how this may not be a major issueÖ
Hynix memory modules
One feature ASUS touts on the EAH3870 X2 1GB TOP is its ďspecially sortedĒ 0.8ns GDDR3 memory. When comparing the EAH3870 X2 1GB TOP to the standard Radeon HD 3870 X2 we received from AMD, you can see that ASUS has indeed opted for faster memory modules than AMDís reference design.
Whereas the AMD reference design relies on 1.0ns Samsung K4J52324QE-BJ1A memory modules rated for speeds as high as 1.0GHz, the ASUS EAH3870 X2 1GB TOP is outfitted with Hynix HY5RS123235BFP-08 modules. These particular memory modules are the fastest chips Hynix makes, and are officially rated for speeds as high as 1,200MHz!
By using faster memory modules, this gives you more headroom for overclocking the ASUS TOP card. Out of the box the memory modules run at 954MHz. This speed is 54MHz higher than the stock Radeon 3870 X2 (which runs at 900MHz), but well shy of the 1,200MHz rating of the memory modules.
This is why we donít think the lack of cooling for the memory modules on the bottom of the card is a huge issue, but at the same time the modules would obviously run a little cooler if RAMsinks had been installed here.
Faster core clock speed
Besides running the memory modules at speeds higher than stock, the graphics core is clocked higher from the factory as well. ASUS clocks the GPU at 850MHz, a 25MHz improvement over the stock Radeon HD 3870 X2.