NVIDIA's Shader Model 3.0, Best Practices provides a deep dive into GPU/CPU bounds and hardware features like instancing and shadow maps.
The Microsoft HLSL Reference details features like the collapsed texture registers and the addition of the "Face Register" for two-sided lighting. How to Check Your Compatibility shader model 3 skachat draiver
For technical analysis and implementation details regarding Shader Model 3.0, you can refer to these papers and guides: NVIDIA's Shader Model 3