I guess it's solved. No screen blanking after 10 minutes, as it was
before, after editing ~/.xinitrc and /etc/X11/xorg.conf.
$ cat ~/.xinitrc
#!/bin/sh
#
# ~/.xinitrc
#
# Executed by startx (run your window manager from here)
if [ -d /etc/X11/xinit/xinitrc.d ]; then
for f in /etc/X11/xinit/xinitrc.d/*; do
[ -x "$f" ] && . "$f"
done
unset f
fi
xset dpms 0 0 0
setterm -blank 0 -powersave off -powerdown 0
xset s off
exec startxfce4
# exec xterm
$ cat /etc/X11/xorg.conf
Section "Module"
Load "extmod"
Load "dri"
Load "dbe"
Load "dri2"
Load "glx"
Load "record"
Load "GLcore"
#Load "v4l"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Plug 'n' Play"
ModelName "Plug 'n' Play"
DisplaySize 305 230
HorizSync 29-98
VertRefresh 50-120
modeline "1152x864" 128.42 1152 1232 1360 1568 864 865 868 910
Gamma 1.0
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>:
"True"/"False",
### <string>: "String", <freq>: "<f>
Hz/kHz/MHz"
### [arg]: arg optional
#Option "SWcursor" # [<bool>]
#Option "HWcursor" # [<bool>]
#Option "NoAccel" # [<bool>]
#Option "ShadowFB" # [<bool>]
#Option "VideoKey" # <i>
#Option "MergedFB" "off" #old debian/ubuntu
Identifier "Card0"
Driver "radeon"
#Driver "nvidia"
#Driver "nv"
#Driver "nouveau"
#Driver "vesa"
#VendorName "nVidia Corporation"
#BoardName "G72 [GeForce 7300 SE/7200 GS]"
#BusID "PCI:1:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
Defaultdepth 24
SubSection "Display"
Depth 24
Modes "1152x864"
#Virtual 3840 1200
EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 1
# EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 4
# EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 8
# EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 15
# EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 16
# EndSubSection
# SubSection "Display"
# Viewport 0 0
# Depth 24
# EndSubSection
EndSection
Section "ServerFlags"
Option "BlankTime" "0"
Option "StandbyTime" "0"
Option "SuspendTime" "0"
Option "OffTime" "0"
EndSection