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Crossfiring the AMD HD6870 review
LAST TIME we looked at the plain vanilla AMD Radeon HD6870 graphics card holding its own against the super overclocked Nvidia Geforce GTX460 from Gainward. This time, we'll see how a pair of those HD6870 cards scale up in Crossfire and hold their own against the Green Goblin's GTX580.
Nvidia's GTX580 is the new king of the single-GPU block until the HD6970 appears in another month or so, even accounting for its freshly rumoured delays. The comparison is also interesting because a pair of HD6870s sell for quite close in actual retail price to a single high-end GTX580, in particular the $550-class overclocked varieties by Asus, Gainward and others.
Since I tested the GTX580 on higher end systems, I set up another fast configuration to review the HD6870 Crossfire pair for a more of apples to apples comparison. I used the Xeon version of Intel Core i7 980X six-core extreme CPU - also known as the Xeon X3680 - together with an Asus Sabertooth X58 high-end mainboard based on MIL-spec grade components. Twelve gigabytes of memory made up of three 4GB A-Data DDR3-1600 high density DIMMs, an 160GB Intel SSD, as well as a Xigmatek 700W PSU completed the setup. Ah yes, there was also the new Xigmatek Aegir 6-pipe heat sink fan assembly, keeping the CPU around 37C at idle, or just 4C above Singapore room temperature. More about these in a separate Sabertooth review.
As you can see here, the two graphics cards fit just nicely into two x16 PCIe graphics slots on the mainboard. Unlike some other high end X58 mainboards, the Sabertooth has no extra PCIe bridges or even x8 - x16 switches, so the latency to PCIe is not affected by any such extra circuitry. Therefore, this should lead to theoretical best scaling measurements, even though the differences aren't large.
We ran the latest Catalyst 10.10 drivers on the usual Windows 7 64-bit operating system, with both 3Dmark Vantage for DX10 and Unigine Heaven 2.1 for DX11.
Here are the results for the single HD6870:
... and for the dual HD6870 Crossfire setup:
As you can see, in both performance and extreme modes, there's quite decent scaling when adding the second card, in fact even better in the Full HD-class Extreme setting with nearly double the score. With that performance, the card pair does perform better than a single GTX580 in 3Dmark Vantage by some margin. On the comparative GTX580 setups, the 3Dmark Vantage results hover around the 24,000 mark in Performance mode and 13,000 in Extreme mode, but taking into account the PhysX offload on CPU benchmarks as well.
Heaven single (top) and dual-card (bottom) results:
However, Unigine Heaven, even in this most recent update, still shows basically no speedup from a dual GPU card setup of any kind.
In summary, while awaiting the HD6970 and HD6990 - which should hand the single GPU performance crown back to AMD - Radeon afficionados can get some pretty decent performance for a few bucks by pairing up two HD6870's in Crossfire. The scaling is good, the cards are reasonably low power - two of them together cost just a bit more than a single GTX580 - and you can have a plenty of display output options with Eyefinity.
In the meantime, AMD's rescheduling of its HD6900 series announcement will hopefully result in a bit higher clock speed for the new cards, just in case they need to keep some distance from the newly resurgent Nvidia. µ
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Couple of months later seems too soon ie 2 - 3 months. If you are talking about holding out for 8-12 months there is no point, the next gen card will be cheaper and faster then adding on a crossfire/sli.
crossfire/sli are not aimed at budget conscious people rather people who go all out. The net result if you delay your purchase by 2-3 months is you still end up paying the same amount.
db, the point is that not everybody can afford to shell out the money required to get one 580 or two 6870 in one go. The possibility of first buying a single 6870 and a couple of months later get another 6870 is what makes this article somewhat valid.
Nebojsa after quickly reading your article your sub title says
"Two Radeons for less than one GTX580, yet the same performance "
So I was like ok then further down you say
"two of them together cost just a bit more than a single GTX580" - Which is true not the other way around I just checked.
Why would you want two cards with a much lower minimum frame rate, twice the noise, I checked the power consumption it is about the same for full load 141 Watts x 2 = 282 for 6870 vs 280 Watts 580. For idle amd solution is 40 watts and nvidia is 20. Plus basing it on one benchmark is not the greatest of ideas.
What ever happened to giving credit to the fastest card? If I were to buy a video card now I would buy the 580. When AMD comes out with their new card and it's fast buy that. You fanboys always get burned for your ignorance.
What an embarrassing build, a dog's breakfast to say the least. Looks like something that big time tech expert Nick Farrell would put together.
Not everyone's unemployed and addicted to Crack, you know... in fact, most people in this economy actually do have real jobs and thus have the financial prowess to acquire such fine technological devices
Who do you know that runs a $,5000 high end desktop system? Engineers? Movie production houses? Who's going to put $5,000 into a gaming system and isn't a "professional gamer"? Why benchmark a system that few people in this economy can afford?? Why not benchmark a system people are actually more likely to buy in this economy? I guess we have to use the latest bleeding edge gear, no matter how few people are actually buying and using it.
Must admit I went crossfire recently with 5770s.
Running a standard run of Heaven in DX11 with one card gave me 32.2fps.
Plugging in the second 5770 pumped it up to 62.5fps.
I know the 5770s scale really well but....
Weird that the heaven bench seemingly only comes in 32bit variety.
upgrading my radeon6870 to 2xradeon6870 basically made my heaven benchmark result skyrocket... from 35ish fps to 65ish.
nub.
In terms of pricing I agree; price/performance on single GPU again I agree its on ATI's side; but crossfire vs single GPU is not the same story; there are still many cases where the minimum frame rates face problems in SLI and/or Crossfire; I would choose at any moment a single card (no matter the producer) that can deliver acceptable minimum frame rates at highest details for every game and not to wait for driver patches
HD6 series, compared to the 5 series, has much better scaling ratio when crossfire. On average the scale up of adding another card is 82-85%, compared to about 75% of 5 series.
I would personally go for HD6850, as it's cost-performance ratio is highest of the two, and maintains the same cost-performance ratio as HD6870 even even at crossfire.
You might have got better performance had you actually plugged it all together rather than appearing to throw everything in the case and hope for the best.
Ever heard of cable ties?