Barring any of the special one-off editions created by vendors like ASUS or GeCube, the last graphics card to have two GPUs onboard had to be NVIDIA's GeForce 7950 GX2 back in 2006. If you can remember, it was hardly the poster boy of dual GPU designs and looked as if someone simply took two GeForce cards and stuck them together. Each core had its own PCB and while it worked like advertised, it was not the most elegant of solutions. Not advertised also was the tremendous amount of heat produced by the card.
Fast forward to 2008 and ATI is the next to try their hand at a dual GPU product. With its new enthusiast level Radeon HD 3870 card unable to pose much of a competitive threat to NVIDIA's GeForce 8800 series performance-wise, this new chipset is ATI's bid to recapture the performance lead. It is also a baptism of fire for ATI's CrossFireX technology, since it underpins the company's concept of multiple GPUs working in tandem. Any failing of this new product will directly reflect the state of CrossFireX technology today.
Aiding its cause is ATI's new 55nm cores that not only promise a smaller die but also lower heat and power consumption. These new cores (RV670) are found in the Radeon HD 3870 and are the basis for the new SKU today, codenamed R680. On paper, the Radeon HD 3870 X2 (kudos to ATI for such a plain but accurate model name) is made up of two Radeon HD 3870 cores on the same PCB, each core having its own satellite array of memory chips for a total of 1GB. Unlike the usual Radeon HD 3870, the cores on this X2 version have been increased from 775MHz to 825MHz. This is however tempered by its GDDR3 memory (as compared to GDDR4 on the single GPU version), which are running at a slower 1800MHz DDR. The high memory frequencies of the standard Radeon HD 3870 at 2250MHz DDR and relating to this, heat and power consumption issues, are probably reasons why ATI has gone for GDDR3 here. Another is likely the higher cost of GDDR4 memory and from our experience with GDDR3 and GDDR4 versions of the same chipset, the performance difference is in many cases not worth the cost.
Therefore, it's close but probably not exactly like two Radeon HD 3870 cards in CrossFire mode. Nevertheless, in terms of pure processing power, this X2 card is no slouch but can it retake the long lost performance crown from NVIDIA's best? We'll examine it after the jump.