If you could try this before doing anything drastic:
* install the PCI GF4MX in the EPIA motherboard like you did before
* boot the PC (I'm guessing there will still be no video)
* now plug the monitor into the onboard graphics
instead of the geforce4 MX.
If you then get a display, I'm guessing it's still running the onboard graphics as the primary adapter. If that's the case (and it's not some esoteric BIOS/motherboard/hardware issue), you can fix it two ways:
NUMERO UNO:
- go into system properties.
- (if you're using windows 2000/XP) click on "hardware", then "device manager".
- under "display adapters", you should see two devices listed - the Geforce4 MX, and the onboard graphics (probably something like "S3 Savage Graphics").
- right-click the onboard graphics adapter, and select "disable".
- the screen will probably go blank, and then your Geforce4 MX PCI should now be the primary adapter.
(by the way, if this does not work as planned, just remove the Geforce 4 MX, reboot in Safe Mode, then re-enable the onboard graphics. It won't affect your hardware permenantly.)
NUMERO DOS:
- Go into Display properties, then click on settings. you should now see two display cards listed - the onboard graphics (which will be Display 1), and the Geforce4MX (which will have a greyed-out monitor graphic).
- Click on "Display 2", and then click on "extend my desktop to this monitor", and then "use this device as the primary monitor".
- click "OK". the display should now go blank.
- switch the monitor cable to the Geforce 4 MX. You should now see the regular windows desktop.
- now you can click on the onboard graphics (probably will still be labeled "Display 1"), and uncheck "extend my desktop to this monitor".
either way, the Geforce4 MX should now be your primary adapter, and the onboard graphics will have been disabled in Windows.
That is, assuming I'm not off my rocker.
[edit]
just to add: i don't have a clue how to do the equivalent in Knoppix.