* a sink side memory of tens of megabytes is either on-chip memory (very costly) or on-PCB DRAM (still costly). For high refresh rate monitors, the memory would

* a sink side memory of tens of megabytes is either on-chip memory (very costly) or on-PCB DRAM (still costly). For high refresh rate monitors, the memory would need to be high BW too. Note that there aren't any modern memory standards that are high BW but low storage. DRAMs with just a capacity of just a few MB would be very much pad limited. * source side, you'd need a shadow buffer as well, and you need double the read BW to detect the difference between previous and the current frame. All of that is technically achievable, but none of it matter for desktop monitors: the power savings are just too low to matter. Laptops are a different matter. Many laptop LCD panels already support self-refresh. (Google "Panel Self Refresh") But that's for cases where the screen is static: the user is staring at the screen, not moving their mouse, the cursor is static. The benefit is not just putting the link but also putting the GPU to sleep. That's the low hanging fruit. Partial screen update doesn't save a lot more, because you'd need to power up the GPU for that.