that one is a 4850, and for about the cover, it depends on the brand of the video card(example, sapphire, powercolor, evga), its their decision on what cover/heatsink/fan to put on on their video cards.
take at look at this article, tomshardware is very reliable.
http://www.tomshardware.com/reviews/best-g...-card,2362.html
should guide you well.
edit: changed the link