Nope, I definitely did that step... a few times. Once I couldn't get it to recognize, I rebooted and ran through all the steps a few times to make sure that I didn't forget anything, and I know that aticonfig --initial --adapter=all is crucial.
But as I said, I put that card in a second machine and it will be a day or two until I have a second card in that machine again. I'll update then. Hopefully the problem will just disappear. Thanks for the help.
P.S.- When adding a second card, Ubuntu wont display anything graphically. My solution has been to enter low graphics mode, follow Humble's tutorial up to aticonfig --initial --adapter=all, and reboot. Those 5870's run really hot until the drivers are working properly though, and I know that can't be a good thing.
That's kind of worrisome. I have 5850's but they didn't do anything like that when I was setting them up. You could always ramp the fans up if it's a problem.
Did you check the xorg.conf (less /etc/X11/org.conf) and see whether the entries were there for the second card.
Section "Monitor"
Identifier "aticonfig-Monitor[0]-0"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
EndSection
Section "Monitor"
Identifier "aticonfig-Monitor[1]-0"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
EndSection
Section "Device"
Identifier "aticonfig-Device[0]-0"
Driver "fglrx"
BusID "PCI:1:0:0"
EndSection
Section "Device"
Identifier "aticonfig-Device[1]-0"
Driver "fglrx"
BusID "PCI:2:0:0"
EndSection