had the same issue on my asus rog- never tried the xfce power manager but solution for me was adding to my ~/.xprofile:

xset s off -dpms

goodluck!

To strengthen our collective security, which is shared among all who care to see- While Microsoft rarely deigns to even give an error code when shit breaks.

Enjoy wailing at whatever enters your imagination.

Your words, they smell of lazy deceit.

I’ve been using this for the past decade, haven’t needed anything else until I started working with Raw files- for those darktable is all I know but it’s also been great.