Tech2 if u want a card that fully voltage adjustable in MSI Afterburner take the MSI GTX460 Cyclone so u can oc it too max, but check W1zzard's Review of both 768mb & 1024mb version here:
MSI GeForce GTX 460 Cyclone OC 768 MB
MSI GeForce GTX 460 Cyclone OC 1 GB
if it was me i will take the 1GB version it got a little higher memory bus and the extra memory might come in handle in some games ^^