Our friend Nate from Legit Reviews encountered a difficult task in his review of ATI Radeon HD 4890 graphics card. While testing the card, Nate discovered that not a single ATI card from the 4000 series render a certain camo mesh in S.T.A.L.K.E.R. Clear Sky v1.5.08. For comparison, the nVidia GeForce line-up has no issues, nor does Radeon 3000 series.
Looking at this scene, everything looks to be normal, typical scene in S.T.A.L.K.E.R.
Now, let's take a look at nVidia's card...
What do we see...? All of a sudden, camo appears. And so is the case with every nVidia card.
The problem lies in the rendering paths - if you select Enhanced Full Dynamic Lighting, the render path is in DX9 mode and ATI 4000 series won't render camo on a specific wireframe, as witnessed in screenshots below. But, if you turn Enhanced Fully Dynamic Lighting (DX10), you won't experience any issues.
While there is something certainly wrong with ATI's to use of different code paths, we can say that ATI focused on DirectX 10(.1) too much, and neglected DX9 users, e.g. players that use ATI's DX10/10.1 hardware in conjunction with the Windows XP operating system. If you use Windows Vista or Windows 7 beta, you should select DX10 codepath and be able to enjoy all the bells and whistles.
Our advice to all of our readers is always the same: when you buy the latest hardware, especially of the high-end flavor - crank everything up to the maximum. We see no reason why would you play S.T.A.L.K.E.R. using DirectX9 render path when playing on DirectX10, or DirectX 10.1, which ATI oh-so touts wherever it can.
Kudos to Nate for discovering the issue.