XPS 13 9350 scrambled screen

9350 occurs frequently, (nearly every time) on warm reboot

often happens whenever system goes into standby

during use it happens occasionally and i have to turn off

on cold reboot, it is hardly ever a problem

you can see the system hasn't hung entirely, some pixels are moving, but no recovery possible without fully turning off the system

I have run full dell system diagnostics, no errors reported

latest BIOS

latest drivers