Visual differences
Stalker: Clear Sky is based on the X-Ray Engine of the predecessor Shadow of Chernobyl. Among enhanced visual effects and better textures, the new Direct X 10 support is advertized. The differences between DX9 and DX10 can be seen in our exclusive screenshot comparison.

But in the game the new effects are visible in certain situations only. Due to the enhanced lighting of objects in Direct X 10, Clear Sky looks more realistic but compared to DX9 the performance doesn't differ very much in our benchmarks. The only option to deliver some noticeable visual differences is the wet surfaces - but they don't cause a real loss of performance either.



Therefore the two versions (DX9 and DX10) are identical in regards of the required hardware but not in regards of the visualization.

(Video) Memory requirements
We decided to test all cards on Direct X 10 and Windows Vista x64, in order to receive the full benefit of 4 GiByte RAM - and Stalker: Clear Sky likes it. The game uses up to 1.6 GiByte memory after some time. In combination with the memory required by the operating system, this exceeds the capabilities of systems with only 2 GiByte RAM and therefore lags are inevitable.

This problem gets worse because of the game's intense usage of video memory. Up to 800 MiByte in DX9 were not uncommon and, according to the console, in DX 10 even more VRAM was used. If you have a graphics card with only 512 MiByte memory, the remaining 300 MiByte are transferred to the system memory. Because of this we recommend 3 GiByte (Windows XP) or 4 GiByte (Windows Vista).

Processor requirements
Stalker: Clear Sky doesn't use more than a single core. Solely the graphics driver sometimes uses an additional CPU core sometimes. Therefore gigahertz and the performance per clock are important.