I've recently done a clean install of 17.04 on a machine with an Nvidia 750Ti card and a Dell 4K monitor. I'm using the Nvidia binary driver 381.09.
All this works great apart from the fact that the display scaling I set in the Ubuntu Screen Display settings always reverts back to 1 when the machine resumes after suspend. I need to set it at 1.5 otherwise everything goes tiny (BTW why doesn't Ubuntu scale to a sensible default with 4K monitors?)
Does anyone else get this? I can't find any mention of it elsewhere.
BTW I've tried the Nouveau driver and that doesn't wake up my screen at all after suspend. So that route's a non-starter.
Edit: Looks like it's been reported as a confirmed bug here Will monitor to see if anything happens.