Most DPMS blankers include this warning in their manual. If your monitor doesn't support power management this software may damage it.
I'm running a double monitor setup: One monitor is a RGB Philips CM8833-II, which i use exclusively for retro gaming and it doesn't support power management of course and the other is a SVGA one which i use for everything else and i have connected it to my gfx card. This one supports DPMS alright.
If that matters, the blanker i'm using always brings the WB screen (C-GFX mode) up front, before it activates the power management signal. The SVGA turns off succesfully. I hesitate to do it while the RGB monitor is ON. I will wait for some input.
Thanks.