9800 XT image quality

Before we get into the DX8.1 versus DX9 comparison, we first want to take a look at DX8 (again, note that these aren’t identical shots of the same scene):

RADEON 9800 XT running DX8.0 path

9800 XT DX8.0 shot #2

Ripples in water more pronounced under DX8.0 w/ 9800XT

Predator still looking good

The DX8.0 path looks quite good

IQ between the 5950 and 9800 XT in DX8.0 looks similar

We can't see any dramatic differences between the RADEON 9800 XT and GeForce FX 5950 Ultra when running the DirectX 8.0 path. Both cards deliver visuals of similar quality.

RADEON 9800 XT with DirectX 8.1:

DX8.1 adds little to this scene

9800 XT with DX8.1. Not much has changed here either

Driver bug on the beams here, ripples in water reduced

Smoke has been added with DX8.1. Unfortunately the flames are a little different than the 5950U, so we cant directly compare those.

RADEON 9800 XT with DX8.1 path

9800XT w/ 8.1 - Output looks similar to the DX8.0 path

DirectX 9 versus DirectX 8.1

As we mentioned at the end of the second page, we were pretty surprised at how similar the 9.0 and 8.1 paths looked on GeForce FX 5950 Ultra, so we took more screenshots with ATI’s RADEON 9800 XT running the DX9.0 path in video stress test:

RADEON 9800 XT w/DX9

Virtual displacement mapping could potentially be in use here instead of bump maps.

Overhead shot, 9800 XT w/ DX9

RADEON 9800 XT in DX9 mode

RADEON 9800 XT shot #5

Final 9800 XT DX9 shot with VST

Here’s where we get our first indication of differences between DX9 and DX8.1. Look closely at the walls of the cave in the first two shots. In the DX8.1 screenshots, the ridges are much more pronounced (the water is also nearly transparent in the second DX9 shot for some reason). We believe Valve is using bump maps to create the walls. You can really see this in the area directly underneath the light in the first image, while in the second picture you can see the difference along the right and left walls of the cave. Here Valve may be using normal maps, or going one step beyond that with virtual displacement mapping:



RADEON 9800 XT DX8.1




RADEON 9800 XT DX9.0


If you refer back to the GeForce FX 5950 Ultra DX9 versus DX8.1 screenshots on page 2, you’ll notice that the FX board in DX9 looks more similar to the 9800 XT’s 8.1 mode than it does the 9.0:



GeForce FX 5950 Ultra DX8.1




GeForce FX 5950 Ultra DX9.0


This pretty much confirms our theory that the FX is running DX9, but in order to prove it, we ran benchmarks with the video stress test. (There are other examples besides the one mentioned above, such as the marble slab in the last screenshot. You can also note differences in the water’s ripple effects in that image as well).