内容摘要：Last monthwe compared half a decade's worth of DirectX 11-capable GeForce cards in the latest and gr

Last monthwe compared half a decade's worth of DirectX 11-capable GeForce cards in the latest and greatest PC games to see where Nvidia has made the biggest performance leaps and which GPUs have aged the best.

We had never compared so many GPU generations under the same conditions and the results were fascinating. So naturally folks using AMD Radeons were also curious to see how their single-GPU flagship parts have held up.

Equipped with five years of Radeon technology and the latest Catalyst driver, we set to benchmark major AMD architectures released between late 2009 and October 2014: Evergreen (HD 5870), Northern Islands (HD 6970), Southern Islands (HD 7970) and the company's most recent GPU architecture, Sea Islands (R9 290X).

The HD 7000 series was a big deal for AMD as it saw the move from 40nm to a 28nm fabrication process. Moreover, it was the company's first truly new architecture in five years since the HD 2000 series.

Known as 'Graphics Core Next' (GCN), the HD 7000 range featured a RISC SIMD architecture that required considerably more transistors than before but offered advantages for GPU computation and also lead to better efficiency. Most of the GPUs in the HD 7000 series were based on the GCN 1.0 architecture, though the HD 7790 featured an improved GCN 1.1 logic, which added AMD TrueAudio and a revised version of AMD's Powertune technology.

GCN 1.2 launched along AMD's Radeon R9 285, featuring improved tessellation performance, lossless delta color compression to reduce memory bandwidth usage, an updated and more efficient instruction set, a high quality scaler for video, and a new multimedia engine for video encoding and decoding.

AMD's upcoming Radeon 300 seriescode-named 'Pirate Islands' is expected to be based on similar GCN 1.2 architecture.

Radeon	HD 5870	HD 6970	HD 7970	HD 7970 GHz	R9 290X
Codename	Cypress XT	Cayman XT	Tahiti XT	Tahiti XT2	Hawaii XT
Fab (nm)	40	40	28	28	28
Transistors (Billion)	2.15	2.64	4.31	4.31	6.2
Die size (mm2)	334	389	352	352	438
SPU	1600	1536	2048	2048	2816
TAU	80	96	128	128	176
ROP	32	32	32	32	64
Memory (MB)	1024	2048	3072	3072	4096
Bus width (bit)	256	256	384	384	512
Bandwidth (GB/s)	153.6	176.0	264	288	320
Release date	Sept-09	Dec-10	Jan-12	June-12	Oct-13
Price at release	$380	$370	$550	$500	$550

The Radeon HD 5870 and HD 6970 were clearly the single-GPU flagships for their series, while the 7970 was replaced after only five months with an overclocked version known as the 7970 GHz Edition, which went on to be the single-GPU flagship for 16 months.

The 7970 GHz was released out of necessity as it allowed AMD to retain the performance crown over Nvidia's GTX 680 – if only barely. This was AMD's answer to avoid immediate price cuts, a move often forced on graphics chip makers after the competition undercuts them in price vs. performance offered. Still, we didn't like the 7970 GHz Edition when it landed as it was more expensive than the standard 7970 and only offered a modest factory overclock. We've included both the 7970 and the 7970 GHz Edition since both were Radeon HD 7000 flagships at a given point.

Let's explore how Radeon GPUs have scaled from one generation to the next over the past few years...