Best Choices for the Money
Before dissecting the results, it seems fairly obvious that if you want to enjoy the latest and greatest PC games with decent quality settings, you'll have to spring for one of the more expensive cards in our round-up. The top contenders include the GeForce GTX 460 (768MB), GTX 550 Ti and Radeon HD 6790.
Having been around since last summer, the GTX 460 is one of the best selling DirectX 11 graphics cards today, possibly only second to the HD 5770. Although the 768MB version of this board is typically about $5 more than the newer GeForce GTX 550 Ti, it provides much better performance.
Considering both the GTX 460 and 550 Ti provide similar power consumption figures, we wouldn't even consider the latter at $145. In fact, when the GTX 550 Ti was released two months ago, we found it to be such a weak offering that we skipped right over it (never reviewed it standalone), and we suggest that gamers do the same.
This leaves the GTX 460 and HD 6790 to duke it out for the $150 throne. Compared to the GTX 550 Ti, the HD 6790 was 11% faster, while it was just 2% faster than the GTX 460 on average. In addition to being slightly faster, the 6790 used a tad less power, so we feel that it is the better choice.
While we won't hesitate to recommend the Radeon HD 6790 at $155, if you're serious about playing demanding games with quality settings beyond medium, you should really consider spending a little extra on the HD 6850 as it offers considerably more performance for a small premium at $175.
Gamers looking to spend under $150 have a few options in the $100 to $120 bracket. The $110 products offered by both companies performed very close to each other. The GTS 450 and HD 6750 were neck and neck throughout our review, with a small 3% positive margin on AMD's side on average.
Even if we ignored that slight margin, the HD 6750 consumed 9% less power under stress testing, making it the more efficient graphics card. Naturally, we must award AMD with the victory here as the HD 6750 gave us superior results -- though it was outclassed by the HD 6770 in terms of performance and value.
Based on our findings, the $120 HD 6770 is currently 8% more expensive than the HD 6750, but it was 12% faster on average. Unsurprisingly, we found a similar trend with the "last gen" Radeon cards, as we always felt that the HD 5770 was a better value than the HD 5750.
The HD 6670 suffers the same fate at $100: it's 17% cheaper than the Radeon HD 6770 yet 27% slower. That kind of performance discrepancy is huge for these budget offerings and it means that the HD 6770 will provide playable performance using decent settings in a wider range of games.
When it came to sub-$100 performance, AMD delivered the goods with the Radeon HD 6570. For a mere $10 extra than the GeForce GT 430, the Radeon offers 44% more performance on average. In other words, the HD 6570 annihilated the GT 430 without breaking a sweat.
Our results were far less one-sided when comparing the $60 GT 520 and $55 HD 6450. While it proved to be an even match, gamers would be wise to forget these cards exist. Neither should be in a gaming rig and that shouldn't come as a shock considering they're entry-level HTPC cards. As a side note, if you were wondering about the gaming performance of Sandy Bridge's built-in GPU performs, it's generally at or below the level of these last two discrete GPUs. A novel feat, but still not up to snuff to run PC games comfortably.
To summarize each bracket: the Radeon HD 6790 trounced the GTX 460 and 550 Ti at $150, while the $120 HD 6770 is in a league of its own as it's superior to all cards in the $100 to $120 range. Lastly, the HD 6570 overwhelmed the GT 430, cementing AMD's dominance over Nvidia in the budget realm.
Update: Intel's Sandy Bridge built-in GPU performance scores have been added in all tests for straight comparison with the most affordable discrete boards.