AMD: Mainstream Cards At Good Quality
Once you duck below the Radeon HD 4870 mark, it becomes necessary to dial the visuals down a bit. The Radeon HD 4850 could probably handle High quality at 1680x1050 without a problem, but in order to simplify testing and generate meaningful numbers through 2560x1600, the following four cards are evaluated using the Good preset.
The 4850, 4770, and 4670 (with GDDR4 memory) are all capable enough at 1680x1050. Clearly the Radeon HD 4550's settings need a bit more massaging to make the card playable, though. That likely means less-demanding options to bring frame rates up.
Performance continues sliding as the game's resolution increases to 2560x1600. And yet, you'll still find the Radeon HD 4850 and 4770 largely playable. Meanwhile, the Radeon HD 4670 drops to the point where it's average frame rate is marginal.
Then again, few folks with 30" displays are likely running three-generation-old video cards and vice versa. So, let's look at 1920x1080 plotted out in one second samples.
For the most part, all three top cards deliver a reasonable experience in this metric.