AnandTech has taken a closer look at the new ATI Radeon HD 3870 X2 dual-GPU graphics card. One of the advantages of this card is that it allows you to use CrossFire on motherboards that don't support it.
The Radeon HD 3870 X2 is built on a 12-layer PCB, compared to the 8-layer design used by the standard 3870. The more layers you have on a PCB the easier routing and ground/power isolation becomes, AMD says that this is the reason it is able to run the GPUs on the X2 faster than on the single GPU board. A standard 3870 runs its GPU at 775MHz, while both GPUs on the X2 run at 825MHz.
Memory speed is reduced however; the Radeon HD 3870 X2 uses slower, more available GDDR3 in order to keep board cost under control. While the standard 3870 uses 2.25GHz data rate GDDR4, the X2 runs its GDDR3 at a 1.8GHz data rate.
The card is priced at $449 which is cheaper than the price of two Radeon HD 3870 cards but does it deliver enough performance? The reviewer says the card is faster than the GeForce 8800 GTS 512MB in most benchmarks but that it can't beat a GeForce 8800 GT 512MB SLI setup. AMD has a small victory today but it's really necessary for them to roll out a new high-end GPU that can really compete with NVIDIA's offerings. CrossFire can work really well but a lot depends on the driver support and if that part is neglected this card may not offer a lot of value in the long run.
For now, AMD should be proud of their achievements. We’re sure many ATI loyalists are going to look at today’s launch as a huge success. Ultimately though, the real long-term value of the Radeon HD 3870 X2 will be determined by AMD’s driver team. If they work closely with game developers and consistently improve performance and scaling for existing and upcoming games, then the X2 is worthy of praise. If the drivers can’t keep pace with hot game releases, however, and users have to wait weeks, or even months to fully utilize their graphics card, that would be a great disservice. We’re hoping for the best, because the hardware is impressive indeed.
You could get enthusiastic about this card but there's no reason to celebrate. This card may be able to tie the performance of NVIDIA's GeForce 8800 GTX but that's a small feat considering the 8800 GTX was launched more than 14 months ago.
Another interesting review can be read at HardOCP, here's a snip from their conclusion in which they compare the card to the GeForce 8800 GTX:
The Radeon HD 3870 X2 does not beat a stock clocked GeForce 8800 GTX right now; it only comes close to its performance level. It took AMD this long to come up with a video card that almost matches a GeForce 8800 GTX in performance and it took two GPUs to do it. That is disconcerting when you consider we are dealing with 640 stream processors on the Radeon HD 3870 X2 versus 128 stream processors on the GeForce 8800 GTX. It really shows how different both GPU architectures are and how worthless comparing specifications has become.