Hey, yeah sleep seems to be an issue it seems to be working for me though on this board at-least but my alien ware x51 r2 sleep is not working.. and i have tried a lot of things to get it to work but i think we will have to wait and see maybe new kexts / updates will solve the issue ( I have tried a-lot of things so far lol darkwake etc.. kexts) so far my issue it it takes 2 mins to sleep properly and then press space bar and it wakes but goes to black screen and sometimes it shows mouse / comes back / white freeze glitches etc..
Several things you can do to see if they help
1- make sure you have a SSDT for your CPU
https://www.tonymacx86.com/threads/quick-guide-to-generate-a-ssdt-for-cpu-power-management.177456/
2-In terminal type the following code and see if something is stopping the sleep
Code:
log show --style syslog | fgrep "Wake reason"
3- Check external usb devices try removing and seeing if something is causing your issue
4- Try Different Smbios I just changed mine for the Alienware to 18'3 Works like champ now