my /home/[user]/.kde4/Autostart/noblank.sh
#!/bin/sh
xset s 0 0
xset dpms 0 0 0
finaly does the trick of noscreensaver and noblank.
tested on the computer club with demo and unatended use between 8.00h-15.30h last saturday

on 4 PCLos machines.
So screen and powersaver cycle are not switched off but set to zero.
See (terminal) xset --help.

Ed