Are you sure thats the 655mhz core model as its supposed to have a large black passive heatsink on the rear of card, I read comments on eVGA forums some peeps got cards without heatsink on rear of cards.
I made sure OCUK looked in little clear window in box to see the heatsink (window where you match up warrenty stickers).
The cards run hot so thats why that model needs a cooler same as you sink the rear chips on your 7000 cards if you voltmod.
http://www.overclockers.co.uk/showproduct.php?prodid=MB-002-EA&groupid=701&catid=56&subcat=877
OR
http://www.overclockers.co.uk/showproduct.php?prodid=GX-032-EA&groupid=701&catid=56&subcat=877
Which is yours, and if its really the 655mhz core model I would swap it for one with a heatsink as eVGA forums says it should have one, I know a few early samples sent to review sites had no heatsinks but the sites stated the retail ones would have the heatsinks.
Also reading the info on eVGA site or in booklet with card, eVGA DO NOT let you change the cooling without losing warrenty. (unless I was really tired and misread).