Hello... a standard GTX460 1GB should have 256 bit DDR5 memory... it is an odd ball configuration... and I recommend looking for that model spec, for purchase, performance, and reliability. I own two... love them.
if i'm not mistaken that card is based on gf114. the original gtx460 using gf104. on nvidia site they called it as gtx460 version 2. my take is those chip are not qualified to make into gtx560 line up so they put this 'reject' chip as gtx460 v2