VESA driver does not seem to work with DPMS

[Kan-I Jyo]

Dear list,

On one of my machines it is loaded with X.org 7.1 with vesa driver 1.2.1.

In order to reduce the power consumption, it is set in xorg.conf to turn off
the monitor if in idle for a period of time(10 minutes here).

However, if using vesa driver, the setting does not seem to work while it
takes effect when switching to the intel driver.

At the same time, the "$ xset dpms force standby" command brings the
monitor into standby mode with intel driver while it triggers no difference
with the vesa driver.

Is is a know limitation of the vesa driver or it is fixed in a recent version?

Any comment would be greatly appreciated.

-- 
Sincerely,

Jyo