First, before anyone else says it, the x800's are quickly fading due to technical problems and shortcomings.
That said, on to yer questions.
Different manufacturers do different things. The chipset is the same, but the manufacturers can do practically anything else they want. ATI only makes the chips. So the manufacturers put on whatever heatsink they want, RAM, colors, etc, as well as what comes with the card, such as games, equipment, manuals, etc.
Some companies issue the cards with bare-minimum heatsinks that aren't totally good enough. To find out how a certain manufacturer does, try searching the net for reviews on different cards made by different manufacturers.
Also, some companies (PNY as one notorious example) NEVER bundle their hardware with games and extra stuff, which sucks. I mean, it's cool to spend $400 on a new card and get a cool game with it! And who the hell wants to spend that much money on a card, and have to then go buy some peice of equipment (like a cable or something)?
Some manufacturers don't offer the same programs for the cards, either. You may get certain card config programs with one mf, but not another.
It all really takes some work looking at the details. What do they offer? Do they have good reviews? How's the hardware (as far as function goes)?
Hope that helps.
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