Remedy have showcased Alan Wake running smoothly on an Intel Core 2 Quad system overclocked at 3.73Ghz with a GeForce 7900GTX.
Markus from Remedy has said “Alan Wake would pretty much not run on any single core processors, although it may be possible to run on single-core Pentium 4 processors with Hyper Threading enabled, with noticably reduced image quality/experience.”
The game will use a separate processing thread dedicated to physical calculations. Since Remedy is using Havok, there is no support for Ageia PhysX cards, so all the physical calculations are done using the CPU. Markus has explained that a normal Core 2 Quad will use 80% of one core for physical calculations.