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Tested: AMD Radeon HD 6870 + 6850 Video Cards

By Norman Chan

Performance is good for the price, but these cards are clearly not high-end.

We gave you a sneak peek at AMD's 6800 series video cards earlier this week, but the embargo on concrete details and performance testing has finally been lifted. The 6800 series represents the first cards in AMD's "Northern Islands" family of GPUs, which is replacing last year's critically acclaimed "Evergreen" family. Evergreen hardware were the first DX11 cards available (beating Nvidia's GTX 400 series parts by several months), and right combination of price, performance and power consumption gave these GPUs a comfortable advantage over Nvidia counterparts--the 5850 remains a great "sweet spot" for most PC builders. 
 
With the 6800 series (codename Barts under the Northern Islands family), AMD is looking to solidify its role as the price/performance leader, with more of an emphasis on price than performance. The cards go on sale today, but we've had the Radeon HD 6870 ($239) and Radeon HD 6850 ($179) for almost a week now, and our testing has yielded some revealing surprises to AMD's strategy. Unfortunately, it's not all good news.


 

The Current GPU Scene

 The awesome Radeon HD 5870

 
On the Nvidia side, the green machine also launched its current generation of GPUs with high-end first: the Fermi-based GTX 480 and GTX 470. It was only months after that Nvidia aggressively targeted the price/performance market with the GTX 460, a $200-$230 card (depending on how much video memory) which has been the most popular Nvidia GPU of this generation. Due to the massive power consumption and heat output of the Fermi architecture (not to mention the massive die size), Nvidia never released a "GTX 495" dual-GPU video card. 
 
The point is, convention dictates that GPU generations are launched with an expensive high-end part that claims the benchmark crown for prestige value, followed by mid-range and budget components for the mass market, and then possibly a dual-GPU ultra card. Today, AMD is breaking that convention with the 6800 series. Barts is not to Northern Islands what Cypress was to Evergreen. Instead, as our benchmarking showed, the 6800 series fits somewhere between the mainstream 57xx and the high-end 58xx parts.
 

Barts vs Cypress

So what's new about Northern Islands, and how exactly is it an improvement over Evergreen? We won't dive into the architectural details too much, but it's safe to say that Northern Islands is an iterative evolution of Evergreen as opposed to a new architecture built from the ground up. As a 2nd-generation DX 11 architecture, AMD emphasized optimization of DX11 features such as tessellation and DirectCompute. And as you can tell by the architecture diagram below, they also shrunk down the die size, though Northern Islands is still build with a 40nm process.
 
Barts is about increased optimization, not increased performance.

post-process filter to smooth out the edges of surfaces and textures as well. Think of it as Anti-Aliasing that looks at the whole of a scene after its been rendered to erase jagged edges, not just the edges of polygons as they're being rasterized. From a performance standpoint, AMD claims that Morphological AA is on par with CFAA, though we were unable to test this due to early drivers. The feature is of course optional, and accessed from an updated Catalyst Control Center.
 
Northern Islands also has refined its Anisotropic Filtering (AF) algorithm for smoother transitions between filter levels. Textures will blend together just a little more smoothly as you look into the distance of a rendered scene. This improvement you get at no performance cost.
 
HDMI 1.4a and DisplayPort 1.2 across all its new cards. Last generation's 5800 cards launched with two DVI ports, 1 HDMI, and a DisplayPort, but you had to use all three types of connections for triple-monitors. There was also an Eyefinity specific model which had six mini-DisplayPorts. 
 
The 6800 series cards all have two DVI ports (one DL-DVI for 30" monitor support), HDMI 1.4a (for 3D compatibility), and TWO mini-DisplayPorts. And with the DisplayPort 1.2 spec, you can actually run six 1900x1200 monitors off of one Radeon 6870. AMD is working with hardware partners to sell a "Multi-Stream Transport" hub (estimated price of $30) that will let you use a singular DisplayPort connection for multiple monitors. And since each of up to six outputs is on a separate controller, your displays will be resolution independent. While I'm not particularly excited about the stereoscopic 3D options offered by DP 1.2 and HDMI 1.4a, I do love the sheer versatility of multi-monitor options enabled by these cards. AMD has taken a clear lead in multi-monitor support with the 6800 series. 


 

Meet the Radeon HD 6870






 

Meet the Radeon HD 6850 



 
Below, I've included a spec chart comparing the new 6800 cards with the current 5800 series cards (including the 5970 just to show you how far away this lineup is from AMD's current champion). I've also included a chart comparing the 6800 cards to Nvidia's 470 and 460 1GB cards, which are their nearest competitors.
 

Speeds and Feeds

SpecRadeon 6870
Radeon 6850
Radeon 5870
Radeon 5850
Radeon 5970
 Transistors 1.7B 1.7B 2.15B 2.15B2x2.15B
 Die Size
255 mm^2
255 mm^2
334 mm^2
334 mm^2
334 mm^2
Compute Cores/
Stream Processors
 1120 960 1600 14402x1600
Texture Units
 56 48 80 722x80
ROPs
 32 32 32 32
2x32
Core Clock
 900MHz 775MHz 850MHz 725MHz725MHz
Memory Clock
1200MHz
1000MHz
1200MHz
1000MHz
1000MHz
GDDR5 RAM
1GB
1GB
1GB
1GB
2x1GB
Memory Bandwidth
256-bit
256-bit
256-bit
256-bit
256-bit
Process
40nm
40nm
40nm
40nm
40nm
Max TDP
151W
127W
188W
151W
294W
Idle TDP
19W
19W
27W
27W
42W
 
 
SpecRadeon 6870
Radeon 6850
Nvidia GTX 470
Nvidia GTX 460 1GB
Transistors  1.7B1.7B
3.0B
1.95B
Die Size
255 mm^2
255 mm^2
529 mm^2
368 mm^2
Compute Cores/
Stream Processors
1120
 960448
336
Texture Units  56 4856
56
ROPs
 32 3240
32
Core Clock
 900MHz 775MHz607MHz
375MHz
Memory Clock
1200MHz
1000MHz
837MHz
900MHz
GDDR5 VRAM
1GB
1GB
1.2GB
1GB
Memory Bandwidth
256-bit
256-bit
320-bit
256-bit
Process
40nm
40nm
40nm
40nm
Max TDP
151W
127W
215W
160W
Idle TDP
19W
19W
33W
22W
 
It can't get any more clear from these specs: even though it would make sense from a naming standpoint, the 6870 is NOT a replacement for the 5870, and the 6850 is NOT a replacement for the 5850.
 

Benchmarking Performance

the $1500 PC we built back in April. It's not a super high-end testbed, but it still has a relatively fresh Windows install (only Steam and web browsers are installed on the system), and is representative of the systems we think most gamers own.

Test Bench Specs

CPU: Intel Core i5 750 @ 2.67GHz
Motherboard: Asus P55
RAM: 4GB DDR 3
HD: Seagate 7200.12 1TB @7200RPM
 
For comparison, we tested AMD Radeon HD 5870 and 5850 (1GB model) boards that we had in the office, along with a 5970. Unfortunately, we don't have comparable Nvidia GPUs in our lab, so those comparisons will have to wait until we fill out our test bench (hey, we're still new and in beta!). But we believe the comparisons with the Cypress cards are enough to show how Barts fits into the current GPU market for purchasing decision purposes.
 
We opted for real game benchmarks as opposed to synthetic tests like 3DMark, to give you a sense of the actual framerates you would get from these cards. We chose a mix of DirectX 10 and 11 games, and ran each benchmark three times. Game settings were maxed out with resolution at 1920x1080 (1080p). We ran tests with anti-aliasing disabled and maxed out in-game (not using the Catalyst Control Panel).
 

Individual Game Benchmark Settings

Crysis: DX10 mode, all settings Very High, using the built-in GPU Benchmark.
Dirt 2: DX11 mode, all settings set to Ultra, using the in-menu benchmark.
Far Cry 2: Both Action and Ranch (Medium) benchmarks, DX10 mode, all settings maxed out.
STALKER Call of Prypiat: Stand-alone benchmark demo, all settings maxed out, DX11 mode.
Civilization V: Benchmarked using FRAPS, "End Game" benchmark setting, which renders a typical large scale game after 300+ moves. All settings set to max, though resolution was automatically lowered by the engine. 
 
Game
Radeon 6870
Radeon 6850
Radeon 5870
Radeon 5850 1GB
Radeon 5970
 Crysis (no AA)
 35.2529.57
39.3435.1
52.75
 Crysis (8x AA)
 29.0624.94
32.18
29.01
46.92
 Dirt 2 (no AA)
 71.962.7
78.8
71.9
100.9
 Dirt 2 (8x AA)
 65.357
69.5
64.9
94
 Far Cry 2 Action (no AA)
 62.9360.71
 62.9762.21
59.72
 Far Cry 2 Action (8x AA)
59.24
52.09
61.86
58.3
57.6
Far Cry 2 Ranch (no AA)
90.33
79.48
96.94
89.1
109.84
Far Cry 2 Ranch (8x AA)
61.3
54
66.6
61.45
92.24
Stalker CoP (no AA)
85.2
70.83
92.6
82.7
123.4
Stalker CoP (4x AA)
48.2
41.66
54
48.9
98.5
Civilization V Endgame
50.6
50.64
50.268
51.078
51.117
 All scores measured in average frames per second.
 

Performance Analysis

he 5870 still remains top dog when it comes to single-GPU AMD cards, while the new 6870 was dead even with the 5850, even with AA turned on. The 6850 unsurprisingly landed at the bottom of the pack, though its average framerates were still very consistent and playable. Keep in mind that is this a $179 card. AMD stresses that because of architecture optimizations, the 6800 series cards are very overclockable, and we're inclined to believe them. Expect third-party board makers to sell pre-overclocked versions of both the 6870 and the 6850.
 

Nasty New Nomenclature

So the Radeon 6870 is the replacement for the Radeon 5850 1GB with the benefits of an optimized architecture and lower price ($239 vs ~$280 for 5850 1GB). I'm fine with that. If you are in the market for a 5850, picking up a 6870 instead is a no-brainer. The same goes with the 6850 and the 5830. AMD actually plans to phase those 58xx parts out anyway with the launch of the 6000 series, while retaining the 5700 series as a budget line. As performers, the 6000 series are very respectable mid-range parts. The problem is, of course, the new naming system. Setting the 68xx series as the mid-range is out of line with the previous generations, which will absolutely confuse consumers. I'm certain that there will be someone shopping for a new video card who will incorrectly assume that the 6870 is better than 5870.  
 
And even if AMD was set on this realignment of their Radeon nomenclature, it could have mitigated some of this confusion by launching Northern Islands with a full range of products so consumers could actually see where each card fits in the budget-to-high-end spectrum. There's no doubt that AMD will eventually announce the high-end of Northern Islands (presumably the 69xx series), so enthusiasts looking for the best of the best will have to wait until then. This release strategy doesn't diminish the merits of the 6800 cards--it's just a frustrating situation.
 

Summary

The upshot, though, is that the 6800 series cards are fine GPUs that will play any modern PC game very well, but are only really appropriate for gamers building new PCs or upgrading from a budget GPU. The DX11 improvements to Northern Islands and aggressive pricing reinforce AMD's price/performance strategy, and have even forced Nvidia to (temporarily) lower its prices on their GTX 470 and GTX 460 1GB cards. The GPU industry's emphasis on giving the biggest bang for your buck is undoubtedly a good thing, though gamers looking for more shock and awe will have to be patient.