Multi-GPU Scaling: Two 3850s = One 8800 GTX?

AMD only sent us a pair of Radeon HD 3850s for this review (believe it or not, we had to beg to get a single 3870), so our only CrossFire numbers come from this setup. That being said, the performance is quite respectable:

Believe it or not, but a pair of these $179 Radeon HD 3850s actually gives you the same performance as a single GeForce 8800 GTX.

 Multi-GPU Scaling (2560 x 1600) Radeon HD 3850 CF GeForce 8800 GT SLI
Oblivion 1.7x 1.87x
Unreal Tournament 3 1.48x 1.66x

 

Scaling looks pretty good from the Radeon HD 3850, however it's still not as good as what NVIDIA is able to achieve with the 8800 GT. NVIDIA consistently achieves about 11% better scaling from one to two GPUs than AMD.

The other problem with CrossFire is that it simply doesn't always work, so a pair of 3850s is not necessarily a better option than a single 8800 GT or GTX. Case in point would be the two other games that we wanted to include here: Quake Wars and Call of Duty 4, both gave us lower frame rates with CF enabled than without. AMD's release notes for the Radeon HD 3800 drivers informs us that some applications may show a performance decrease with CF enabled, so we're not too surprised.

While it'd be nice to be able to purchase two cheap cards and get better performance than the best out there, there are simply too many caveats to really embrace the idea.

Out with the Old, in with the Mid-Range Power Consumption
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  • Locut0s - Thursday, November 15, 2007 - link

    Well yes I know but the "cores" that they are using are extremely simplified, more so than I was thinking of. Instead I was thinking of each "core" as being able to perform most if not all of the steps in the rendering pipeline.
  • Guuts - Thursday, November 15, 2007 - link

    I think the simple answer is that in the CPU world, they hit a clockspeed wall due to thermal issues and had to change their design strategy to offer greater performance, which was to go to multiple cores.

    The GPU makers haven't reached this same wall yet, and it must be cheaper and/or easier to make one high-performing chip than redesigning for multi-GPU boards... though there are some boards that have 2 GPUs on it that act like SLI/Crossfire, but in a single board package.

    I'm sure when the GPUs start suffering the same issues, we'll start seeing multi-core graphic cards, and I would assume that nvidia and AMD are already researching and planning for that.
  • dustinfrazier - Thursday, November 15, 2007 - link

    Going on a year for Nvidia dominance and boy does it feel good. I bought my 8800gtx pair the first day they were available last year and never expected them to dominate this long. God I can't wait to see what comes out next for the enthusiasts. It get the feeling it is gonna rock! I really wanna see what both companies have up their sleeves as I am ready to retire my 8800s.

    I understand that these latest cards are great for the finances and good energy savers, but what does it matter if they already have a hard time keeping up with current next gen games at reasonable frame rates, 1920x1200 and above? What good does saving money do if all the games you purchase in 08 end up as nothing but a slide show? I guess I just want AMD to release a card that doesn't act like playing Crysis is equivalent to solving the meaning of life. Get on with it. The enthusiasts are ready to buy!
  • Gholam - Thursday, November 15, 2007 - link

    For the reference, over here in Israel, 8800GT is promised to arrive next week - for approximately $380 + VAT (11.5%). For comparison, 8800GTS 640MB costs a bit over $400+VAT; 8800GTS 320MB used to cost in the low to mid 300s, but they're no longer available. I wonder when will 38xx get here, and at what price...
  • abhaxus - Thursday, November 15, 2007 - link

    let me just say that i love my 8800 gts. however, as a person stuck with a 939 athlon x2 @ 2.5 ghz, and wanting to upgrade to a quad core setup, I've been freaking out lately about what motherboard to buy, and the lack of new video cards has made that very difficult. If the 320mb gts dropped in price in relation to the new GT, I'd buy a 650i/680i board in a heartbeat and just SLI it up. But the fact that no innovation is going on has kept prices too high for too long. I've had this card since march and prices are actually higher now than when I bought it originally.

    At least intel isn't resting on their laurels the way nvidia has been. I want new cards... so the old ones get cheaper!

    also if anyone wants to go really OT with a reply and tell me whether an Asus P5N32 SLI Plus would be a good choice to O/C a Q6600 to about 3.2 ghz and run 2 8800 GTS 320mb cards in SLI... let me know :)
  • wolfman3k5 - Thursday, November 15, 2007 - link

    No, the P5N32SLI wouldn't be a good choice to overclock a Quad. Neither would be the Striker. The fact of the matter is that both this ASUS boards have a hard time putting out high FSB clock and sustain them with Quad Cores. You either go EVGA 680i (LT) if you want to retain the SLI capability, or I would suggest a P35 or X38 based motherboard.
    Just my 0.02C.
  • abhaxus - Thursday, November 15, 2007 - link

    I've read that... but then I've also read on AT and that with current bios releases the asus boards are fine to around 360-400 FSB. I haven't O/C'ed an intel chip since the Celeron 300A so I am pulling my hair out trying to decide if it's worth it to plan for going SLI or just get a P35 board and stay with a single card.
  • Anand Lal Shimpi - Thursday, November 15, 2007 - link

    <font color=black>
  • abhaxus - Thursday, November 15, 2007 - link

    I apologize for breaking the comments... silly me for mentioning another site :)
  • bupkus - Thursday, November 15, 2007 - link

    Just highlight the blank areas with your mouse.
    Click and drag.

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