Debian Multimedia :: DPMS Works Only For A Moment

I'm using Debian Jessie on amd64. I have this video card:

Code: Select all01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [NVS 310] (rev a1)

I'm using the stock nouveau driver that ships with Jessie, and loads by default. I installed this card during my botched attempt to upgrade from Wheezy. This is a fresh install, and DPMS isn't working right.

I can run "xset dpms force off", and the screens will blank. I even see the "HDMI signal lost" screen of both (identical) monitors. However, before the power LEDs of either monitor go orange (instead of blue) the screens come back on as if I had made mouse or keyboard input. If I've locked the screen with xscreensaver, the screens are blank (I use only the blank hack). I've forgone the use of xscreensaver for now, believing it to be contributing to the problem. If I run "xset dpms force off" now, the screens blank, but the "HDMI signal lost" screen doesn't show, and the screens immediately unblank.

Here's the output of "xset q":

Code: Select allxset q                                                                                                                                                                                           
Keyboard Control:
  auto repeat:  on    key click percent:  0    LED mask:  00000000
  XKB indicators:
    00: Caps Lock:   off    01: Num Lock:    off    02: Scroll Lock: off
    03: Compose:     off    04: Kana:        off    05: Sleep:       off

[Code] ...

It's like something is preventing the screen from going blank, but I don't know what it could be.

I installed the proprietary nvidia driver. Sadly, it does the same thing, so that's one thing I can cross off as the likely culprit.

Ran this command:

Code: Select allxset dpms 0 0 0

So when "xset dpms force off" is called, it powers down the monitor immediately. I will be reverting back to nouveau, and will report whether the problem resurfaces.