Celeron substitution

Archived from groups: alt.comp.periphs.mainboard.elitegroup (More info?)

On an old PC I have one motherboard ECS P6BAT-A+ (PCB:2.0) with the
last version available of BIOS (version 5.6).
On this card I mounted a Celeron 433 MHz that I have replaced today
with a Celeron 633 MHz (given to me from a friend who has changed PC).
The problem is that after to have mounted new CPU the PC is ignited,
the impellers turn but does not work, the screen remains extinguished
and the hard disk remains inactive (does not load data).
On the web site of ECS they say that the CPU is supported with this
version of the BIOS. The page that attests it is
http://www.ecs.com.tw/ECSWeb/Suppo [...] 48&LanID=0

On what it depends? How I can arrange the problem?

Thanks
Apu