Yes the card you are using is most likely a 3.3v card prob using AGP1x or AGP2x (ie VERY old), your new mobo AGP slot is most likely not a UNIVERSAL AGP Slot and as such only works with newer AGP card which use 1.5v and AGP4x or AGP8x. If you had a Universal AGP Slot then you could plug in all new and all old cards (I think this is still true even of AGP3.0 so long as it's Universal). Any gfx card since and including GeForce1 and the Radeons are 1.5v so the card you are trying to use must be VERY old (3dfx?). Considering the costs of Radeons and GF4MX cards it doesn't seem worth using anything less on any remotely modern PC. That is with a bit of guess work, but basicly if the notches / keying doesn't match up then the card and the mobo slot are not compatible.