[dba-Tech] Auto Power-up doesn't work

I have a PC which used to be on 24/7 and I want it to run only during 
daytime now.
Therefore I have set the BIOS power up control to
Auto Power up..........Everyday
Time alarm...............08:00:00

the other parameters in this section are set as follows:
AC PWR Loss restart......................enabled
PWR up on external modem act..........disabled
wake on LAN or PCI Modem..............disabled

does anybody have any idea whether there are any other parameters to set?
I am using auto power-up with other PCs just fine. had never before tried it 
with this one.
this one is about 4 years old.

thanks in advance for any help/comments
Lembit