The Radeon HD 4850 & 4870: AMD Wins at $199 and $299by Anand Lal Shimpi & Derek Wilson on June 25, 2008 12:00 AM EST
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Due to circumstances quite beyond our control, this will be essentially the third time we've covered the Radeon HD 4850. AMD has managed to make the $200 price point very exciting and competitive, and the less powerful version of RV770 that is the 4850 is a great buy for the performance.
As for the new business, the Radeon HD 4870 is not only based on an efficient architecture (both in terms of performance per area and per watt), it is an excellent buy as well. Of course we have to put out the usual disclaimer of "it depends on the benchmark you care about," but in our testing we definitely saw this $300 part perform at the level of NVIDIA's $400 GT200 variant, the GTX 260. This fact clearly sets the 4870 in a performance class beyond its price.
Once again we see tremendous potential in CrossFire. When it works, it scales extremely well, but when it doesn't - the results aren't very good. You may have noticed better CrossFire scaling in Bioshock and the Witcher since our Radeon HD 4850 preview just a few days ago. The reason for the improved scaling is that AMD provided us with a new driver drop yesterday (and quietly made public) that enables CrossFire profiles for both of these games. The correlation between the timing of our review and AMD addressing poor CF scaling in those two games is supicious. If AMD is truly going to go the multi-GPU route for its high end parts, it needs to enable more consistent support for CF across the board - regardless of whether or not we feature those games in our reviews.
That being said, AMD's strategy has validity as we've seen here today. A pair of Radeon HD 4850s can come close to the performance of a GeForce GTX 280, and a pair of Radeon HD 4870s are faster across the board - not to mention that they should be $50 less than the GTX 280 and will work on motherboards with Intel-chipsets. Quite possibly more important than the fact that AMD's multi-GPU strategy has potential is the fact that it may not even be necessary for the majority of gamers - a single Radeon HD 4850 or Radeon HD 4870 is easily enough to run anything out today. We'll still need the large monolithic GPUs (or multi-GPU solutions) to help drive the industry forward, but AMD raised the bar for single-card, single-GPU performance through good design, execution and timing with its RV770. Just as NVIDIA picked the perfect time to release its 8800 GT last year, AMD picked the perfect time to release the 4800 series this year.
Like it's RV670 based predecessors, the Radeon 4850 and 4870 both implement DX10.1 support and enable GPU computing through their CAL SDK and various high level language constructs that can compile down SPMD code to run on AMD hardware. While these features are great and we encourage developers to embrace them, we aren't going to recommend cards based on features that aren't yet widely used. Did we mention there's a tessellator in there?
On the GPGPU side of things, we love the fact that both NVIDIA and AMD are sharing more information with us, but developers are going to need more hardware detail. As we mentioned in our GT200 coverage, we are still hoping that Intel jumping in the game will stir things up enough to really get us some great low level information.
We know that NVIDIA and AMD do a whole lot of things in a similar way, but that their compute arrays are vastly different in the way they handle single threads. The differences in the architecture has the effect of causing different optimization techniques to be needed for both architectures which can make writing fast code for both quite a challenge. The future is wide open in terms of how game developers and GPGPU programs tend to favor writing code and what affect that will have on the future performance of both NVIDIA and AMD hardware.
For now, the Radeon HD 4870 and 4850 are both solid values and cards we would absolutely recommend to readers looking for hardware at the $200 and $300 price points. The fact of the matter is that by NVIDIA's standards, the 4870 should be priced at $400 and the 4850 should be around $250. You can either look at it as AMD giving you a bargain or NVIDIA charging too much, either way it's healthy competition in the graphics industry once again (after far too long of a hiatus).