DX9 vs. DX10

As with every DX10 capable title, the first question that pops in everyone’s mind is what the benefits of using DX10 over DX9 are, and what kind of a performance decrease should be expect because of it. To answer your first question the benefits of DX10 aren’t all that big, often times being incredibly hard to spot, but they do come with hardly no performance drops associated. Breaking the enhancements down, they fall under one of the 3 categories:

You will most likely agree with us when we say that the list isn’t all that impressive, and save for the dynamic water ripples not of these features sounds like something you’d even notice in the first place. But why waste words explaining it, when we can use screenshots to let you see.

Note: Because JPEG is a lossy image format, for the purposes of these comparisons we are using lossless PNG format without scaling. This gives a true and accurate representation of in game image quality. If you see image comparisons on other sites and they are in JPEG format you could very well be looking at jpeg artifacting (compression abnormalities) and not the rendering quality of the actual game! The downside to using PNG is that the images will take much longer to load, so if you are on a slower connection you may wish to avoid clicking the thumbnails.

If you don’t know what to look after here, you’re probably scratching your head and wondering why we used the same (well, almost) screenshot two times. Take a look at the DX9 picture, and notice the sharp edge where the fog particle (a sprite in this case) touches the wall. On the DX10 picture the situation is similar, but the sharp edge is blurred, giving the impression that the fog stops at the wall and doesn’t go through it. Not the biggest effect in the history of graphics, but a nice touch all the same.

Here the difference between DX9 and DX10 is more apparent. In the first screenshot the ugly water ripple effect stands out on its own. Compared to the very pretty pixel shaded water effect the 2D sprite splash just doesn’t do justice to the games graphics. In DX10 the nasty sprite gets replaced with a dynamic pixel shader effect. It is not perfect, as you can sometimes see the sharp edge where the effects end (especially in motion), but overall the ripples look a lot better.

Again, the screenshots tell the whole story. Whereas in DX9 the shadows can be quite pixilated at times the DX10 shadows look a lot better. Both use soft edges, but the DX10 shadows are displayed at a higher resolution, making them look almost real.

Couldn’t they have been created in DX9?

All three effects are obviously rather basic and could most likely be done in DX9 as well. Why 2K decided to tie them in with DX10 we will probably never know, but one of the likely reasons is that the performance hit associated with turning them on is almost nonexistent. We ran several batches of benchmarks on a wide variety of cards and the results confirmed this. All of the results were within the 2% margin of error, regardless of card. Even AMD/ATI cards didn’t lag behind by more than 3% with the newest drivers, contrary to the widespread belief that 20%+ drops are common (they were before the 7.9 driver set).

To avoid making you stare at graphs that look like mirror copies of each other we decided to look at how the game performed under Vista (with either DX9 or DX10 enabled) and then compare it to the performance under Windows XP. All tests were performed with the latest drivers (see Test System page for more info). The scene used for testing was one from the beginning of the game, when the player first enters the Medical Pavilion.

As expected the only two cards capable of running Bioshock at 1920x1200 with a stable framerate were the 8800GTX and the HD2900XT. What surprised us however was the huge performance boost the HD2900XT received when going from DX10 in Windows Vista to DX9 in Windows XP. As a result even the 8800GTX wasn’t able to keep up with the HD2900XT anymore, lagging behind considerably. This didn’t happen in Vista, where all cards (including the HD2900XT) remained within a 2 fps difference  between DX9 and DX10.

The lower end of the scale sees the 8600GTS and 8600GT struggling to keep up with the load, failing miserably in Vista, but remaining playable under Windows XP. Similarly the HD2600XT didn’t have what it takes, staying in-between the two cards in both occasions.

Once again the performance difference of the HD2900XT staggered us. While the 8800GTX managed to come closer in relative terms, the 6fps difference remained in place. Under Vista the exact opposite happened – the 8800GTX stayed well ahead of the HD2900XT, especially if you look at the maximum fps value. The result was a noticeably more stable framerate at times when there were tons of particle effects on the screen.

The lower end cards still weren’t in the green at 1600x1200, though playing with 25fps isn’t all bad. In Windows XP the HD2600XT managed to catch up with the 8600GTS, while the 8600GT remained a bit behind. The 3fps difference might not sound like much, but when that makes more than a 10% decrease you can’t help but notice it.

Testing the two behemoths from nVidia and AMD at such a low resolution seems kind of pointless, but considering many still have 17 inch LCD screens that can’t go beyond 1280x1024 we still wanted to include them. The story from before repeated itself, with the HD2900XT almost doubling its framerate under Windows XP. The 8800GTX also received a 26fps boost, this time almost catching up with the AMD card. If we went as far as 1024x768 that just might have happened.

This resolution is far more interesting when it comes to the rest of our card lineup. The 8600GTS came out on top in Vista, though just barely. This minor lead was lost in Windows XP, where the HD2600XT not only caught up, but even beat the card (Max value only though). The 8600GT as before stayed slightly behind, though this time around the performance wasn’t half bad even in Vista with DX10 on. Overall all three cards produced a smooth and enjoyable experience in Windows XP, with only the 8600GTS and the HD2600XT delivering something similar in Vista.