Architecture, specifications, and design highlights for the AMD Radeon HD 6850 and Radeon HD 6870 – this is what everyone has been waiting for. While many sites are publishing exhaustive dissertations spanning many pages, we’re looking to quickly bring out the essentials of what you need to know. The time for guesswork regarding AMD’s 6000 series graphics cards has come to an end and benchmarks are publishing at many sites as you read this. In the absence of solid facts alongside a plethora of supposed “leaks”, the buildup to the release of the AMD 6000 series was fed from a consistent diet of rumors, guesswork, and imagination. Sites and communities have lit up with discussion regarding what to expect and with few reliable facts to work with the discussion has a way of turning rabid. As much as we all enjoy getting fired up and trying to figure out whats coming next, everyone welcomes solid details and specifics – its time we take the rumors out behind the shed and give them the “Old Yeller” treatment. Unlike the end of the Disney movie however, I doubt any of us will shed a tear laying these rumors to rest! Fortunately I gained some first hand insight in talking with AMD in LA a week ago, and I’ve been burning to bring this information out to our readers. It’s time to pull the trigger so let’s get started.
6850/6870 Quick Summary
The top AMD slide above is a quick-summary confirmation of what we are dealing with in the Radeon 6800 series – generational refinements upon the 5000 series architecture. The second slide is important in how it frames the 6800 series – looking at the X axis we have “Compute Power/Launch Price” against “Performance per $ in GFLOPS”. The positioning of the Radeon HD 6850 and Radeon HD 6870 in the discrete graphics market is a primary factor targeting the sweet spot of the market around $200. The focus these pictures present is on communicating the improvements and work that went into refining the architecture while reducing the cost for the consumer, but let’s break down these details. For starters, its important to understand that the first statistics presented are comparing AMD’s 5850 against the 6870. “More performance per mm²” and “over 35% better than previous generation” begs qualification so let’s take a look at the math and ensure we are setting expectations correctly. AMD used 3dmark Vantage Extreme to benchmark performance on the following testbed:
- AMD Phenom II 1090t (3.2GHz) processor
- Gigabyte 890FXA-UD5 motherboard
- 8GB DDR3 memory at 1600MHz (timings: 9-9-9-24)
- Windows 7 RTM 64bit
- Driver version 8.782RC1
In this test, the 5850 scored X7403 compared to the 6870 which scored X7730. That doesn’t sound like much of a difference and there is good reason for that – there is only a moderate improvement in performance on this benchmark with the 5850 vs 6870. Underwhelmed? Try not to get ahead of me here! As mentioned previously, this slide is demonstrating architectural refinements so lets look closer at the size of these chips. The 5850 comes in at 336 mm² while the 6870 shrinks things down to 255 mm². So while the performance improvement of the 6870 is moderate in 3dMark Vantage Extreme, the performance per mm² is rather remarkable:
- Radeon HD 5850 – 7403 (performance)/336 (mm²) = 22.03
- Radeon HD 6870 - 7730 (performance)/255 (mm²) = 30.31
Crunching those numbers, we see that actually “perf per mm²” is 8.28 points better on the Radeon HD 6870 which comes out to a 37.5% improvement that AMD rounded down to a nice even 35% for the slide. Similar but better performance from fairly remarkable architectural refinements… Everyone loves a good car analogy right?! You can use a car’s engine compartment as a metaphor – your engine design needs to be more efficient and perhaps a bit more elegant to do more with less. I spent a bit of time focussed on this single statistic and thats because it strikes to the core of the character of these cards – optimizations doing more with less.
What More Are We Getting?
2nd generation DirectX11 design brings faster tessellation and geometry throughput.
AMD reports twice the tessellation performance with the 6870 compared to the 5870 based on “AMD internal synthetic testing”. I don’t know about you but the first thing that makes me think is that I’ll need to see some benchmarks – however its important to note that tessellation performance is very sensitive to the number of pixels per polygon.
We’ve all seen that NVIDIA favors the Unigine Heaven benchmark in promoting the Fermi architecture, and this is related to the level of tessellation used in the benchmark. This is relevant because the Fermi architecture is particularly strong in floating point performance which is great for tessellation however floating point performance is considerably less important in real world gaming. Bringing this line of thought full circle draws out the fact that you have to be careful when considering synthetic benchmarks – they do not always reflect the level of performance you can expect while gaming.
For this reason, AMD took some extra time explaining that the sweet spot in their perspective is aiming for around 16 pixels per polygon to ensure the best image quality with efficient performance – too many pixels per polygon and performance can suffer, too few and image quality deteriorates. Fortunately for AMD, with being the first to market with DX11 support in the 5000 series a lot of game developers designing for DX11 built using AMD hardware. AMD was the only DX11 game in town for a solid 6 months and its reasonable to think this lended some influence to AMD regarding design decisions throughout the development process while they worked with developers to optimize performance on their hardware.
Why did I take the time to explain that? It’s a point AMD spent some time on, and the message it is looking to demonstrate is that in actual game performance it can be very unlikely for you to see the stark performance contrast you can find in a synthetic benchmark. In reading on Overclockers Forums, I recently read a forum post which I’ll loosely paraphrase – “There are lies, damn lies, statistics, then benchmarks”. Sometimes that can hold pretty true, so as potential buyers who want to be happy with our purchases, its important we take a well measured evaluation when looking at benchmark results to ensure they are setting our real world performance expectations accurately. If a particular benchmark draws an unexpected outstanding result that contrasts with results in many other real world benchmarks, its likely a particular feature of that benchmark rather than a permeating advantage of the card.
Enhanced Image Quality
New anti-aliasing modes and better anisotropic filtering bring better image quality to the table compared to the 5000 series.
Looking at AA we have something called “Morphological AA” which can be enabled in Catalyst Control Center. This brings full scene AA accelerated with DirectCompute that processes more elements in a way thats faster which improves image quality while offering more performance than other AA levels. It works with any game in DirectX 9, 10, or 11. Anisotropic filtering has also had its algorithm improved reducing visible filtering imperfections.
The CCC has also had user interface improvements made to the way you can control texture filtering and Catalyst AI.
What Less Are We Working With?
Less GPU area at 255 mm², less power draw, and less money out of pocket with both cards coming in below $250. The following images summarize the exact technical specifications, and highlight how AMD has managed to tighten up the 6800 series yet deliver some solid performance for the price.
Bottom Line: Moderate Performance Improvements, Competitive Pricing
This has been a bit short and sweet with the Overclockers.com review sample still bouncing through the postal system. If you haven’t picked up on the chorus throughout this article this final heading puts it in a nutshell for what you can expect to find once we publish our review, or as you read elsewhere around the net. This introduction to the 6000 series clearly has a heavy focus on price/performance targetting the moderately priced gaming GPU segment. Keep in mind however that AMD has expressed strongly that they’ve been listening to what gamers want, and they are focused on delivering it. While these cards address the “sweet spot” and break the lid off the AMD Radeon 6000 series, if you find yourself still waiting to have your hair blown back there are more good things on the horizon.
Stay tuned, we’ll have our own hands-on review up soon, and in the meantime we’ve already published a round up of a few other great reviews while you wait!