CMOS setup for Dell Optiplex GM 5133

[phoneguy1]

I'm trying to access the CMOS setup for a Dell Optiplex GM 5133 with a Phoenix BIOS V1.10 A20.  Most older Dells seem to be F2 during POST to enter setup, but not this one.  I've tried everything I can think of (Esc, Del, F8, etc) - anybody know the magic key?  Dell support doesn't seem to have anything on a unit this old.  Trying to get it up and running to support some older DOS stuff.
Thanks  -the new guy-  

[Computer_Commando]

I have yet to see a Dell that was not in their database.  What is the Service Tag?

I think CMOS setup is ALT-ENTER
It's usually displayed on the POST screen.

Update:

Found it on Dell's website:
http://support.dell.com/support/edocs/dta/stingm/00000005.htm

from DOS
CTRL-ALT-ENTER

[phoneguy1]

Commando? Seems more like guru to me.  Been so long since I worked on a Dell, I forgot about the Service Tag.  Used it on their site and presto - found the Ctrl - Alt - Enter, as you found also (way ahead of me, I might add).  Guess that's why I'm the "newbie" and you're the expert.  Thanks for the quick and accurate response.

Once I got to the setup, I was able to match the hard drive type with the gently used one I just put in and VIOLA!  we have C:> prompt.  Kind of makes the heart beat faster!  Thanks again :+)

[Computer_Commando]

...Been so long since I worked on a Dell, ...

Me, too.  I knew it was "something"-Enter.  I think it's  unique to Dell.