Conclusion, an unusual one...
Despite featuring twice as much video memory, the HD 2600XT was unable to match the 8600 GTS on more than one occasion. Truth be told, these mid-range performance products are not nearly as fast as we expected them to be, though this has been known for quite some time now. The GeForce 8600 GTS is roughly as fast as the previous generation 7900 GS, depending on the game used for testing.
If we were presented with a 7900 GS and a 8600 GTS, and then told to pick one, we would most likely grab the 7900 GS every time. Given there is very little price difference between the two, we imagine most of you would do the same.
A similar scenario is presented with the Radeon HD 2600XT, which is also much slower than we had hoped for. Given that the 512MB version we used today does cost roughly the same amount as a Radeon X1950 Pro, we would also pick the latter over this new DX10 mid-range solution.
This is an interesting situation and not one we have ever encountered before. Almost a year ago we compared the GeForce 7900 GS and the Radeon X1950 Pro head to head to determine which would be the better buy. Back then we recommended the Radeon X1950 Pro over the GeForce, despite of the fact it cost considerably more. The Radeon X1950 Pro was an impressive performer and not only for its time, today we are still finding this graphics card to be an exceptional performer.
Just recently we published a Bioshock videocard performance article which showed the Radeon X1950 Pro polishing off the very two (new generation) graphics cards tested today. So given a $150 budget, we would still pick the Radeon X1950 Pro over all current offerings. From a gamer's point of view the only thing the X1950 Pro lacks is DirectX 10 support, which in my opinion works to be the same if we had it or not on the Radeon HD 2600XT and GeForce 8600 GTS anyway.
The whole point of DX10 is to improve visual quality, and so far we have seen almost no games taking full advantage of this new rendering technology.
Elaborating further on this subject, the problem becomes that these mid-range graphics cards are too slow to play DX10 games. Sure, you can use the GeForce 8600 GTS to play Bioshock in DX10 mode, but in order to achieve playable performance, the visual settings must be shut down a notch and things like shadows that actually look a bit better in DX10, must be turned off.
In other words, because the older Radeon X1950 Pro is actually faster, it can deliver more playable rates using higher quality visual settings and therefore will look better in DX9 when compared to a GeForce 8600 GTS running in DX10.
Arguably as more titles are released to take advantage of DirectX 10, this scenario might change. But then if you think that DX10 is Vista exclusive, and any game developer on its right mind will release games that are backward compatible with Windows XP at least for the next 18 months, there is a narrower possibility of regretting our decision.
Therefore, in our comparison between the Radeon HD 2600XT and the GeForce 8600 GTS, we have found the Radeon X1950 Pro to be the winner, go figure.
Thanks go to Visiontek for sending us the Radeon HD 2600XT board we tested today. They make good products including Radeon X1950 Pro boards in both PCIe and AGP flavors, so check them out.