I would recommend the HD Radeon 5870 Eyefinity6 to someone looking to create and Eyefinity setup. I think the incremental cost of $80 is quite reasonable considering the extra 1GB of frame buffer and the additional Eyefinity configurations the E6 card brings. In my mind the real issue of investment is not between the two 5870 cards, but between the Eyefinity6 and the HD 5970.
Based on current demand and initial supplies, the E6 is retailing for about $499. The HD 5970 is still running $699 to $749. From what I've seen in my benchmarks, and in reading the forums, the HD 5970 looks to be a great card - but it is a dead end. With the 5970 card you get blazing fast speed, but you are locked in to three screens with no real options for expansion.
Forum members have not been able to get the 5970 to run in CFX with another 5970 (Quad-Fire) or a 5870 (Tri-Fire). Additionally, my benchmarking proves that the 1GB framebuffer becomes a bottleneck when paired with multiple-GPUs. I do realize the 5970 is clocked slightly lower than the 5870, but I don't believe that solely accounts for all the difference.
On the other hand, a single Radeon 5870 Eyefinity6 gives you 2GB of frame buffer, additional display options, and the ability to run two E6 cards in CrossFireX. My CFX setup ran first time without a hitch.
Make no mistake about it - 2GB of VRAM is not needed to play any game today in 3x1 Eyefinity. However, you won't be able to do it at max settings and consistently hit 60fps. You will have to reduce quality, sometimes to the point of virtually abandoning the DX11 code path and feature set all together.
Extra VRAM used to be coveted for things such as bigger textures (those are still out there), bigger resolutions (and those are getting bigger), and anti-aliasing (though 2x is probably fine, really). However, in todays gaming landscape there are many new things vying for your framebuffer - HDAO, Hard Shadows, Tessellation and Full-Screen Post Processing to name a few.
Two 2GB is not a requirement today. Most DX9 titles and less than Eyefinity resolutions simply won't take advantage of the second gigabyte. However, if you want to take advantage of these newer technologies being introduced in DX11 and coming into the maturity from DX10, then 2GB will be your friend. It can smooth out existing gameplay experiences, and open doors to experiencing new DirectX features. This will be even more crucial with 3x1 Eyefinity and Beyond.
For the $80 price difference between the original HD 5870 and the Eyefinity 6 (which also brings six monitor outputs), I would consider the investment a hedge against speedier obsolescence. Even if you don't believe me, or think ATI is offering something you don't need - take a look at their competition. NVIDIA is launching the first reference cards in the new GTX400 (Fermi) line with 1.25GB and 1.5GB. Apparently they see the current or future need for greater than 1GB of frame buffer as well.
The 3x2 Eyefinity setup is great in creating a huge single mass of displays. Putting six 1080p displays in one location provides over 12M pixels at your disposal, with great options for multi-tasking. For me the middle bezels are a gaming deal breaker, and the physical height of the panels can be a hinderance.
Like the initial release of the Radeon HD 5870, ATI leaves me wanting more. Last time it was Bezel Compensation and better Intermediate Resolutions. They delivered those in Catalyst 10.3 and 10.2, respectively. This time they leave me wanting the 5x1-Portrait configuration. I know that an internal driver is floating around, and hopefully it won't be long before we start to hear more about it. I won't even mention that 7x1-Portrait would still get under the "8k limit" in Windows with 1920x1080 panels (7560x1920 with a 16:4 aspect ratio ^_^)
There is still the lingering issues of Profiles not working consistently. I had them working on the 10.3 Preview driver, but lost them with 10.3a. Granted by that time I had layered about a half dozen drivers on top of each other over the life of this install, and run through almost a dozen video card combinations.
The 10.3a Preview driver was sent out to fix some blanking and sync issues with 5+ panel installs. The driver initially left me with some issues. Once I finished my benchmarking and had time to set up a new clean install, the issues were indeed addressed. I hope for the same thing with the Profiles and Hotkeys.
I will probably go back and re-examine Batman:Arkham Asylum with 2xAA. And, I would like to get in an RTS and MMO. I got World in Conflict, but couldn't get the benchmark properly due to some missing texture issues. I'm hoping the clean install will fix that as well. I have figured out a horse ride I can take through Lord of the Rings Online that will give me a repeatable event. It will also allow me to test DX9, DX10 and the upcoming DX11 patch.
I also want to go back through and figure out what settings you need to hit 30fps or 60fps at 3x1 Eyefinity with each of the cards that supports Eyefinity. I did that for the 5400, 5500 and 5600 for widescreen and it was an interesting experience.
I have tested every card that ATI offers from the 5450 through the 5970. This review basically covers the benchmarks on what they consider "Ultra Enthusiast" (the Eyefinity6 and the 5970, along with CrossFireX), as well as the top "Enthusiast" card (the original HD 5870). I plan to put together reviews for each of the remaining card markets: Mainstream (5400, 5500 and 5600), Performance (5700) and Enthusiast (5800).
With all that data, and the information on "Hitting 30/60", I should have all the data points needed for a complete Eyefinity Buyers Guide. The goal will be to help you pick a GPU, and monitor configuration based on the games you play and the performance you want.
I've been working with the folks at Ergotech about a stand for 5x1-Landscape. They sent me a longer center bar, so that I could fit all three middle monitors on the flat surface. From there, the outer monitors sit on the wings and angle toward the center. There are a few more details I'd like to look at, but I think we have something cool in the works. Once we get it all put together, Erogotech has said this will be their first WSGF-branded SKU. Cool, eh?
ATI has produced a compelling product with the Radeon HD 5870 Eyefinity6. It offers great options for configuration and expandability. Unless you're looking to go for 5x1-P or 3x2, I don't see the immediate need for any existing Radeon 5870 owner to rush out and buy the card. Though, if you are playing the DX11 games the 2nd GB helps, I'm sure you're original HD 5870 would fetch a good price on eBay. This would be a good time for one of ATI's partners to offer a trade-up program.
However, if you are looking for a bigger upgrade or to start fresh with Eyefinity, I don't see a reason to choose the original HD 5870 over the Eyefinity6. The extra features and options are well worth the price differential.
If you are certain you will only ever be running 3x1 panels and want the fastest card today, then the HD 5970 is still for you. But, I do see the Eyefinity6 as the better option for the long term with its ability to use CrossFireX.