Will a Quadro K600 and Quadro K4000 work together in sli mode to drive single UHD 4K display monitor for cad cam and digital media?

No, a Quadro K600 and Quadro K4000 cannot work together in SLI mode, as NVIDIA's SLI technology requires identical GPUs. Additionally, the Quadro series generally does not support SLI for CAD and digital media applications, as they are optimized for different workloads. For driving a single UHD 4K display, it's best to use a single powerful GPU, such as the K4000, for optimal performance.