I just got three AGP Geforce 256 and few Geforce 2MX videocards (yes,with that "key"),what I have been told, "not working at all".
Checked them all in different BX motherboards laying around (PCPartner,ASUS P2B-F),and all videocards are working perfectly!
May be, voltage regulator for AGP port isn't powerful enough in that particular MSI motherboard...