Which of modern (desktop PC) CPUs would provide best performance in single-threaded applications?
There are some games that haven't been optimized for multi-core use, and the CPU speed is their bottleneck (for physics calculations primarily).
I know the end of the line in the gigahertz race were Intel's single-core CPUs of over 4GHz, but then the companies began scaling the speed back while adding more cores or features like hyperthreading. Support for these old extra-fast single core CPUs is scarce nowadays, plus older motherboards, slower RAM and AGP cards would create new bottlenecks, so a more modern alternative would be preferred. So, which of modern CPUs is best suited for this kind of operation?