Generally F means either the mainboard is toast (system failure) or that 
the DCOK line hasn't come on yet. What kind of chassis are you in and are 
your power supplies sufficiently loaded? If so then you may have a dead CPU 
card. Another possibility is that you didn't seat it completely/correctly 
in the CPU box.

--Chuck

At 09:41 AM 4/15/01 -0600, you wrote:
>Hi,
>Just tried to upgrade my 4000/400 to a 4000/600.
>
>Nu success :-(
>
>I guess, it's simply exchanging the CPU boards, right ?
>Anything else to do ?
>
>The new board just stucks with an "F" on the LED.
>
>thanks for any help in advance,
>emanuel