My guess is, its just a low quality card that dell have put their own bios on. ( by modding whatever bios it came with). The extra pipes/ soft shadow may be disabled because it was tested faulty when the card was made. sometimes cards with some faults on are just given their own bios to help them function at an acceptable level. And yes, its true, a 7300 uses the same core as a 7600 etc, they decide what a cards going to be based on what the core can do ( same way all p4 prescotts are the same chip, just tested at their best stable value and marketed at that speed.) be very careful with the bios, id recommend using an editor if you can rather than a straight forward flash.