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Last response: in Graphics & Displays
February 21, 2008 6:32:04 AM

There are some pre-tests about CrosfireX scaling in Anandtech. The 3 cores seems to be sweet spot at this moment, but maybe we will see more benefits from additional cores in the future. The best part is that even at this moment the CrosfireX seems to work ok with selected aplications. We will see some more supported aplications added before CrosfireX is officially released in the next month.

Game Resolution AA AF Detail Settings
Half Life 2: Episode Two 2560 x 1600 8X 16X Highest in-game
Unreal Tournament 3 2560 x 1600 0X 16X Highest in-game
Bioshock 2560 x 1600 0X 1X Highest in-game
Call of Duty 2560 x 1600 4X 16X Highest in-game
Crysis 1920 x 1200 0X 1X High Quality defaults

Number of GPUs HL2 UT3 Bioshock CoD4 Crysis
1 x Radeon HD 3870 39.3 46.7 36.9 25.3 14.0
2 x Radeon HD 3870 (1 X2) 71.9 84.1 63.2 50.0 26.2
3 x Radeon HD 3870 (2 X2 + 1) 93.3 112.7 86.7 72.2 26.4
4 x Radeon HD 3870 (2 X2) 102.2 114.6 92.5 93.2 27.7

Single to dual GPU scaling is similar with SLI as CrossFire, but the 2-way to 3-way gain is better on CrossFireX. NVIDIA's quad-SLI is not yet available so we're not sure how the 4-way scaling will compare, but so far it seems like CrossFireX is doing quite well in the pure numbers game.

Due to the state of AMD's driver optimizations DX10 games currently only scale well to 3 GPUs and not much beyond (Crysis/Bioshock), while DX9 games will generally scale better all the way up to 4 GPUs.

More about : crossfirex

February 23, 2008 6:38:49 PM

There is one more CrosfireX test available:

The result are in format: min/average/max frames

Bioshoc 2560X1600 0xAA 8xAF
4 GPU 42/91,5/168
3 GPU 50/84,2/151
2 GPU 45/64,9/112

CoD4 2560X1600 4xAA 8xAF
4 GPU 7/63,9/218
3 GPU 8/55,8/170
2 GPU 14/43,1/120

UT3 2560X1600 0xAA 8xAF
4 GPU 42/57,7/63
3 GPU 24/53,9/63
2 GPU 41/58,1/63

Crysis 1280X1024 HIGH 4xAA 8xAF
4 GPU 25/38,1/48
3 GPU 15/37,4/47
2 GPU 10/25,2/32
1 GPU 10/19,1/25

Drivers, drivers, drivers... Nice to see some improvement in Crysis minimun frame rates. But if the driver does not support multible GPU cores in particular game, you have got big room heater and nothing else!

February 23, 2008 6:43:14 PM

I wanted to know if this crossfirex would improve scaling on 2 cards voer teh current method. AMD are very sketchy about this.
Related resources
February 23, 2008 6:48:12 PM

Hatman said:
I wanted to know if this crossfirex would improve scaling on 2 cards voer teh current method. AMD are very sketchy about this.

I think not, because CrosfireX is just ATI's way of doing xGPU driver. Of cource there will be some improvements in 1 GPU and 2 GPU, because ATI cards are so driver dependable, so any improvement in this area should improve the overall speed allso. IMHO
February 29, 2008 8:47:46 PM

Even one more CrosfireX preview.

Bioshoc 2560X1600 0xAA 8xAF
4 GPU 42/91,5/168
3 GPU 50/84,2/151
2 GPU 45/64,9/112

CoD4 2560X1600 4xAA 8xAF
4 GPU 7/63,9/218
3 GPU 8/55,8/170
2 GPU 14/43,1/120

Crysis 1280X768 HIGH 4xAA 8xAF
4 GPU 20/40,3/61
3 GPU 20/40,2/58
2 GPU 21/31,2/40
1 GPU 15/26,2/33

This seems to be a collasion of previous. The only difference is smaller resolution in Crysis.
March 1, 2008 11:10:28 PM

And one mmore with mixed cards... well it's possible, but is it a worth of it?

CoD4 1920x1200 resolution with 4x AA
3850 23,09
3870 25,80
3870+3850 44,48
3870 X2 49,35
3850+3850 51,30

Bioshock 1920x1200
3850 31,2
3870 39,5
3870+3850 57,0
3870 X2 57,7
3850+3850 57,1

3DMark 2006 1028x1024
3850 10717
3870 11950
3870+3850 15907
3870 X2 16473
3850+3850 16506

Legit Bottom Line: Mixing Radeon HD 3800 series cards can be done without losing stability and the performance gains are very nice.

I'am somewhat surpriced. I was expecting that mixing 3850 and 3870 would suffer more...
March 6, 2008 2:35:47 PM

Catalyst 8.3 is out: CrosfireX analyce and something more...

With multi-GPU configurations, avoiding CPU limitations is a very important issue at driver level - at the end of the day, enough CPU horsepower is still required to deliver frames to multiple GPUs in a timely fashion, an issue which becomes more important the more graphics cores (and thus the more frames required to be 'stacked up') you add. If the CPU can't keep up with providing those frames to the GPUs to work on, your multi-GPU scaling and performance begins to dip. ATI have worked hard to load balance everything as much as possible to avoid these CPU limitations, while also optimising the communications and calls between the graphics driver and CPU to be as efficient as possible.

March 6, 2008 3:15:54 PM

Hey, I am still a little confused. It's great news that Catalyst 8.3 is out, and therefore now ready to support CrossFireX, but where are all the motherboards that support it?

Are any motherboards available yet that support CFX? And which chipsets support it?

Thanks in advance.
March 6, 2008 3:23:41 PM

Just to clarify, I want to pick up two HD3870X2's now, and I have an Intel Q6600. So I need a motherboard that supports the Intel processor and CrossFireX. I have no idea what to look for. Does the X38 chipset support CFX?

Thanks again.
March 6, 2008 4:37:23 PM

X38 should support it as far as I know. Specifically the Maximus Formula series does and is a great choice.
March 6, 2008 7:28:54 PM

Kataklyzm said:

Are any motherboards available yet that support CFX? And which chipsets support it?

  • RD480 / 480X
  • RD580 / 580X
  • 7-series Chipsets
  • future AMD Chipsets

  • Glenwood (955 / 975)
  • Broadwater (P/G965)
  • Bearlake B (P/G35)
  • Bearlake X (X38 / X48)

    So allmost any AMD or Intel motherboard will do...
    March 6, 2008 7:38:49 PM

    You wont need a crossfirex mobo for two 3870 x2s. You should be able to do that in any crossfire mobo with the 8.3 drivers and Vista.
    March 6, 2008 8:24:42 PM

    i am waiting for crossfirex benchmarks to go up ( thought there would be tons by now ) I have an x38 board with two 3870s now.. what I want to see is the scaling of my set up now compared with 1 3870x2, and one 3870 as well as against 2x 3870x2s. if the gain between 3 GPUs and 4 is not that much.. ill just get a 3870x2.. but if the 4th gpu adds enough of a boost.. ill sell both my 3870s and get 2 X2s
    March 6, 2008 9:44:25 PM

    Here is one from a trusted site(IMO)
    The test system was running Windows Vista Ultimate 64-bit with all available Microsoft updates including the hotfixes required for enthusiast video cards to run correctly. The CrossFireX testing was done with CATALYST 8.3 beta drivers and CATALYST 8.1 drivers were used on all the other Radeon HD graphics cards. NVIDIA Forceware 174.12 drivers were used on all GeForce graphics cards. All results shown in the charts are averages of at least three runs from each game or application used.

    If the Beta is the same as the final release there is much good to be said for this release!!!

    These just seem to be using the ATI/AMD marketing material
    March 6, 2008 10:16:45 PM

    Those are great results. going to be ordering a X2 soon 8).. just hope it scales good with Crysis 8)
    March 7, 2008 12:11:59 PM

    can u hook up 4 3870 x2 to a crossfirex
    a b U Graphics card
    March 7, 2008 2:20:57 PM

    Haha, no. Just like you can't do Tri-SLI with the GX2...think about it, 6 G.P.U.s in SLI....would be nice.
    March 7, 2008 4:58:05 PM

    i thought gx2 didn't support sli!
    a b U Graphics card
    March 7, 2008 5:47:16 PM

    Hmmm, i have seen pictures or 2 in SLI around the web, maybe the final profuct won't be SLI supported.... it wouldnt surprise me if I was wrong.
    March 7, 2008 6:15:34 PM

    Gx2 times two will be possible.
    March 8, 2008 4:53:09 PM

    Now Anandtech review:

    Now a review with sli comparison!

    Oblivion 4xAA/16xAF Performance
    1024x768 1280x1024 1600x1200 1920x1200
    NVIDIA GeForce 9600 GT SLI 72.7 55.4 45.3 26.1
    NVIDIA GeForce 8800 Ultra SLI 98.1 78.5 68.3 43.3
    NVIDIA GeForce 8800 Ultra 53.8 42.4 36.1 23.1
    NVIDIA GeForce 9600 GT 36.9 29.2 25 15.6
    AMD Radeon HD 3870X2 (x 2) 106.1 93.3 78.1 54.5
    AMD Radeon HD 3870X2 + 3870 87.6 73.6 62.9 42.3
    AMD Radeon HD 3870X2 64.4 53.6 46.6 31.7
    AMD Radeon HD 3870 36.4 30.9 24.4 16.7

    If you want our honest opinion, right now CrossFireX is sitting way out on the razor-sharp bleeding edge. When it works, the results can be very impressive. When it doesn't, the headaches, BSODs, uninstalling, reinstalling, and hacking that may be required is enough to make the best geeks cower in fear.