[CentOS] Keeping machines online

I am using centos 5.1. I want to keep my machines always powered on.
Some machines (important ones) are UPS'd.

I have also set in the BIOS (gigabyte motherboard) the power options
that after power loss should do a full on.

The other day we had just a momentary power drop.
the UPS machines had no issue of course with that.

However, the other machines did not come back on.

Is there anything additional in Centos that can help ensure
this machines turn back on. Perhaps something in acpi stuff?
Does that need setup?

Thanks for the discussion.

Jerry