Detailed Features: ASUS EAH5870 V2

With high-end video cards, the cooling system is an integral part of the performance envelope for the card. Make it run cooler, and you can make it run faster has been the byword for achieving gaming-class performance with all the latest and greatest GPUs. The ASUS EAH5870 v2 uses a fairly standard GPU cooler design that is similar to the reference design, but it contains some enhancements, some more visible than others.

Three large diameter heatpipes pass directly over the GPU die and then spread to the outer reaches of the fin assembly. It's obvious to see, but the entire fin assembly is constructed from copper, which is a significant performance upgrade from the typical set of aluminum fins. Two of the heatpipes are 8mm diameter and the shortest one, that is also closest to the blower wheel, is 6mm. ASUS does not use the direct contact method here; instead a thin copper plate is what interfaces directly with the top of the GPU. Considering the power density of modern GPU devices, it makes sense to contact every square millimeter of the top surface with the heatsink if you can. I shake my head in wonder when I see 5-pipe direct-contact designs where the outer two pipes don't contact the GPU at all!

The air all flows in one direction, from the front of the card towards the rear and then out the rear vents, for the most part. There are several relief vents cut into the shroud, but the majority of the heated air exits out the back of the case. I always check to see how much air is exiting the case while I'm benchmarking, and to see how hot it is. The ASUS EAH5870 v2 makes good use of the larger vent on the back plate, made possible by the deletion of the second DVI port, which most of the other cards squeeze in. This design, even more than the reference cards, is well suited to multi-card CrossFireX applications.

The GPU makes contact with a copper block that is soldered to the three heatpipes passing directly over the top of the GPU. The thermal interface material (TIM) was evenly distributed by the factory, but was still piled on thicker than necessary. Excess TIM can cover up sloppy assembly methods, but for the most part I've only seen even distributions that indicate a certain amount of care was used to mate the two surfaces. The TIM was applied to the top surface of the GPU and then spread out once the HSF was mounted. For a thorough discussion of best practices for applying TIM, take a look here.

The memory chips and all the power transistors that make up the business end of the VRM are all cooled by contact with the large aluminum frame that holds everything in place. Two smaller voltage regulators, which are rated for 2 amps each, get linked in as well. Thermal tape makes up the difference in heights between all the individual chips and provides for a pretty foolproof assembly process. Various sections of the plate are cut out to provide clearance for the taller components on the PCB and to provide spot ventilation.

The main power supply controller chip used on the ASUS EAH5870 V2 is a UP6208AM chip, a 12-phase PWM control IC that supports I2C software voltage control, just like the more expensive Volterra chips used on the reference 5870 boards. In this application, ASUS is using seven of the twelve available phases to provide 6-phase power to the GPU and a single phase for the DRAM. There are also two other uP6205 controllers to generate VDDCI and MVDDC, and a couple of uP7704 2A linear regulators included for supplying some smaller loads on the board.

The ASUS EAH5870 v2 uses standard LFPAK^TMpackaging for the MOSFET power transistors and drivers in the VRM section. This discrete implementation gives up the opportunity to save space, but it does provide the designer a broader choice in component selection, compared to a DrMOS design. The 6030AL devices installed here can source a whopping 79A at an ambient temp of 20C, and are downgraded to 56A at 100C.

The memory choice for the ASUS EAH5870 V2 video card is consistent with the HD 58xx reference designs. The basic HD 5870 specs only require 1200 MHz chips for the memory, but most cards have been using these Samsung K4G10325FE-HC04 GDDR5 parts, which are designed for up to 1250 MHz. Only a few folks have successfully overclocked this RAM above 1300 MHz, but meeting its rated spec of 1250 is generally a cakewalk, an easy upgrade from the stock speed of 1200 MHz. Since the SmartDoctor software supplied with this Voltage Tweak edition doesn't have the capability to modify memory voltage, don't presume that you will get more than the rated memory speed.

We've spent a lot of time in this review on the board design, because we've seen a lot of variation in the 2nd generation HD 5870 cards that ATI partners are releasing lately. The first cards on the market were all reference designs, and even some of the early custom cards from ATI AIB partners, like the Sapphire Radeon HD5870 Vapor-X we reviewed last November, used the reference PCB with all of its electronic design features intact. Now that we've examined some of the unique features and details of this latest generation card from ASUS, let's put the EAH5870/V2 to the test in the next major section of our review.

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