https://bugs.freedesktop.org/show_bug.cgi?id=100270

--- Comment #8 from brett.hassall@gmail.com --- As a workaround:

install acpi-call-dkms run - echo "_SB.PCI0.PEG0.PEGP.SGOF" | sudo dd of=/proc/acpi/call

Power consumption once settled after login (no wifi connection) drops to previous 4.7 kernel levels (ie from approx 11,1W to 6.5W)