ASUS EAH6870 DirectCU ReviewRHKCommander959 - January 17, 2011
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The ASUS EAH6870 DirectCU has a direct contact copper triple-heat pipe base. In case you were wondering, the CU in DirectCU is the elemental symbol for copper. A backplate provides rigidity and has heat fins and although the memory is not actively cooled on either side, this may be a simple fix for interested users with thermal tape or something similar. The 6870s only have a single crossfire slot so only two can be used at a time by default. Connectivity is through two DVI ports and two DisplayPorts. The GPU core is fabricated on the 40nm node at TMSC, with the 1GB of GDDR5 connected through a 256bit memory bus. The core is overclocked to 915 MHz while the memory is clocked at the stock speed of 1050 MHz.
The fan shroud hangs off around an inch from the end of the PCB, with the design exhausting the heated air back into the case. There is a grill on the expansion plate that can help some heat exhaust if the case it is installed in utilizes a positive pressure effect. The card is mostly black and metallic grey with some nice red lines on the shroud and the ASUS logo to accent the card. Between the large heat sink and backplate, this card has virtually no give to it and should provide a great base for the heat sinks to mount evenly to the PCB components. The backplate can get in the way of certain PCI Express slot locking mechanisms. A simple enough fix can be had by removing the latch although it can pose an inconvenience. The ASUS Sabertooth motherboard has the conflicting latch style although as long as the motherboard tray is sturdy and perfectly aligned, the latch can be left in place and still work, albeit barely. Out of the box, the ports/slots are protected by blue plastic covers to keep them clean and free of oxidation, always a welcome feature on any graphics card although that has never been a problem for me personally.
The 6870 requires two 6-pin PCI Express power connections and an open x16 length PCI Express slot for installation. The heat sink and shroud are offset with the actual graphics card giving it an interesting look while also increasing the length, it should fit any standard case unless something is nearby such as a hard drive or drive rack.
The card has two DVI ports, one is a digital port (top) while the other is integrated (bottom) for digital and analog output such as VGA conversion. Two DisplayPorts are added with a screw holding each one firmly in place as to avoid breaking them loose from the PCB during use. The back of the graphics card shows some capacitors and exhaust ventilation, along with the 4-wire PWM fan.
The 6870s and 6850s are technically midrange for the 6-series AMD offerings even though they pack a good punch. So, they are equipped with only a single Crossfire slot meaning only two can be used together. Two 6-pin PCI Express power connectors are needed to power this card.
The heat sink uses three copper heat pipes to disperse heat into the cooling fins, the base uses direct contact to dissipate the heat immediately from the core although the GPU die is exposed so only the immediate contact patch receives the heat from the GPU. This is most likely the best means of heat transfer as a integrated heat shield (IHS) is actually another thermal barrier designed to protect the core more than disperse heat. The GPU core is protected by a shim, this helps keep the corners of the die from getting cracked when the heat sink is being installed, the core is rather large for a supposed midrange offering. The Super Alloy Power MOS chips are cooled by a small aluminum heat sink that screws into the back plate. Using this system, the pressure is evenly dispersed when compared to PCBs that do not have any sort of backing plate where the chips in the middle might not make contact with the heat sink. All eight Hynix memory modules are on the GPU side.
The backplate uses spacers and ten screws to sandwich the graphics card between itself and the heat sink. The four standard screws hold the heat sink while six others mount the PCB to the back plate. A thermal pad covers the GPU core's backside area to help lower temperatures introduced into the PCB. The plate has fins on it to help dissipate heat that it may absorb. The rest of the plate is covered in plastic to keep from grounding to the PCB. The back of the card is void of any main components, mostly electronics for the core/memory and solder joints.
The die size is approximately 255 mm². Far smaller than the midrange GTX 460 from NVIDIA that is estimated to be somewhere around 370 mm². The i7 CPU has a core size of 263 mm² to put it into a CPU perspective! The GTX 480/470/465 all have a die size of 529 mm² as the GTX 470 and GTX 465 use the same core as the GTX 480 with parts disabled. This is nearly twice as large as the 'Barts' Radeon HD 6800 core. Both AMD and NVIDIA have their cores produced at Taiwan Semiconductor Manufacturing Company (TSMC) on the 40nm fabrication process. The 6870 was intended to be an efficient 5850, improvements stem from the redesign that lowers Stream processors while improving tessellation and DirectX11 performance. The Hynix GDDR5 memory ICs have part number H5GQ1H24AFR-T2C, meaning that they are rated for 1.25 GHz at 1.5 V. The memory doesn't need direct cooling as it operates efficiently enough to not overheat.
Time for the specifications and features!