I have a D510MO board, running 64-bit Arch Linux. Ever since I first got it a few weeks ago, my monitor connected to it won't turn off via DPMS. Originally it came with BIOS v0175, I have since upgraded to v0210 and now v0303, with no change in the problem. I have tried multiple different monitors to no avail.
The monitor does not turn off when commanded to do so with "xset dpms force off" or "xset dpms force suspend". It just displays the "Cable not connected" OSD message. On another system with the same monitor, the LCD display will briefly say "No signal" before turning off as expected.
DPMS is enabled and working as far as the software stack is concerned. I am beginning to wonder if this may be a hardware problem, and if so hopefully can be fixed with a BIOS update.
I have filed bug report for the display issue here: