OK. Solved this. I went into the BIOS configuration and enabled Power Management->USB Wake On Sleep. Now, KB and mouse input will wake the system.
I recently purchased a Precision 3630 tower. I am using a Microsoft wireless KB and mouse on a USB 2.0 port. Based on Device Manager, the only USB ports that allow power management functionality are the USB 3.0 ports. Is this correct? The reason I ask is I'd like to use the mouse or KB to wake the system from sleep. On my old Optiplex desktop, this was possible since the USB 2.0 hub supported PM. That does not seem to be the case with the Precision 3630. How are folks waking their Precisions from sleep (other than pressing the power button)? Thanks!
Precision 3630: Which USB Ports Are Power Managed?