Two are often better than one, something AMD has taken to heart with its latest high-end offering, the HD3870 X2 (RV680). The recipe seems simple: take one very large PCB, add two GPU cores, mix and stand back and watch the feathers fly.
The two GPUs in question are two of AMD/ATI’s latest HD3870 (RV670) items, which are placed one in front of the other lengthways on the PCB, itself measuring some 27cm in length. The card is so long that it is the full width of an ATX format motherboard, which might cause problems with SATA ports, etc., on the motherboard, let alone trying to fit it in a case.
Built on a 55mn process which cuts both the power requirements and the heat generated by the core, the HD3870 features DirectX 10.1 and SM4.0 support along with UVD (Unified Video Decoder), PCI-E 2.0 support and CrossFireX support.
The two GPUs of the X2 are linked by a PCI-E 1.1 interconnect, with bi-directional x16 PCI lanes between the two working as Crossfire would with two separate cards, but the external interconnect of the card is to the latest PCI-E 2.0 specification.
Using a cooler which runs the length of the card, and with a single cooling fan at the far end of the cooler, warm air is pushed out of the card via a grille on the expansion plate. The fan works efficiently, and an added bonus is that it does so reasonably quietly.
Both the core and shader clocks on the X2 have been tweaked 50MHz over the standard HD3870 so they run at 825MHz instead of 775MHz. On the memory front both the type and clock speed of the X2 are lower than the standard HD3870. Instead of 512MB of GDDR4 clocked at 2,250MHz, the X2 has 1GB of GDDR3 memory running at just 1,802MHz.
Above the cooler at the fan end sit the two power connectors, one 6-pin and one 8-pin PCI-E, which, unless you have a new power supply, may cause a problem. You can use two 6-pin connectors, but without using the 8-pin one you can’t fully benefit from AMD’s Overdrive, the company’s overclocking utility which is part of the Catalyst Control Panel.
Sapphire’s take on the HD3870 X2 is to use the standard reference design, even down to the red PCB, with the only change being the sticker on the cooler. But as with most Sapphire high-end cards you get a useful bundle of bits in the box.
The software bundle is made up of the Driver CD, Cyberlink PowerDVD and DVD Creativity Suite and a copy of Futuremark’s benchmarking suite, 3DMark06. The hardware bundle consists of a Crossfire bridge cable, HDMI dongle, two DVI-VGA dongles, two 6-pin PCI-E power cables and an RGB-out cable.
So, down to the nitty gritty: how does the card perform? Well, we thought we would go for the current game of the moment and the one that also eats graphics cards for breakfast, namely Crysis. At a lowly resolution of 1,280 by 1,024 with 2x Anti Aliasing and all settings set to high, the X2 gave a frame rate score of 30.5fps, just short of Nvidia’s 8800 Ultra (36.7fps) but better than the single core HD3870 (22.8fps).
However, once the resolution was ramped up, the second GPU of the X2 made its presence felt. At 1,920 by 1,200 pixels with the same detail settings, the X2 came out on top with a score of 34.5fps as opposed to the Ultra’s 27.7 and the HD3870′s 22.8.
The one thing to remember about Sapphire’s HD3870 X2 when you compare it with Nvidia’s mighty GeForce 8800 Ultra is the price difference. The X2 costs around £270-£280 whereas you won’t get much change out of £450 for the Nvidia card, which gives the HD3870 X2 an astonishing bang for your buck.
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