Fresh on the heels of my Windows 7 upgrade, I also upgraded my video card so I could play Borderlands. It's kinda stupid but Borderlands requires a graphics card which supports DirectX 10 and my old Radeon X800XL only supported 9, although I'm sure it could have handled the game.
Being a pseudo-ATI fan, I looked at ATI cards and since this was a rushed and unexpected purchase, I decided to buy something cheap. In the end I went for a Sapphire Radeon HD 4670 with 1GB of memory. I paid only $70 for it.
I'm very happy with this card so far. Although I could have paid about double the amount for a better card from the 4800 series, I decided not to due to the fact that it wasn't a planned expense and because the more expensive card also uses a lot more power, gets hotter and is much louder. From various reviews I gathered that the 4670 is very silent even at full load. I am happy to confirm that this is true.
I played Borderlands for a couple of hours and the card runs great, at 1280 x 1024 and high detail. It stayed silent throughout.
As for WoW, it runs same as ever. I don't see any tangible difference.
Patch 1.0.5 commentary
4 years ago