The Coolaler.com forum has posted pictures of what appears to be the RV670-XTX card. Actually, a sticker on the back of the card shows that it is a RV670-XTX card. The leaked card has a 256MB of memory on the 256-bit memory interface.
It is based on a 55nm GPU that works at 600MHz. The PCB is the same length as the HD 2900XT card and it is an Engineering sample made by ATI. It has a six pin power connector and uses eight Hynix HY5RS573225B GDDR3 FP-11 memory chips which are rated to work at 900MHz.
You can check out more pictures here.