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CrossFire Scaling Results: 3DMark And Crysis

PCI Express And CrossFire Scaling: Is P55 Good Enough?
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3DMark shows the horrible effect of putting a high-performance graphics card in a low-performance slot, as two Radeon HD 5870 graphics cards consistently beat the P55 three-way configuration.

Yet 3DMark as a pure synthetic doesn’t show us how bad adding a third card in x4 mode can really be. For that, we could look to the most difficult game in our arsenal, which is Crysis.

Three cards are worse than two when paired with the P55. But also notice that two cards perform far better with the X58 than with the P55 in the Crysis benchmarks. This phenomenon is certain to be a limitation with CrossFire on x8 slots, although we expect it will appear only with super-bandwidth-hungry titles.

The X58 continues its lead at very high details and 4x AA, at least until we reach 2560x1600. We’ve seen the problems with running this last combination of settings on multi-card arrays several times in the past and are almost ready to ignore the setting.

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  • 16 Hide
    gkay09 , January 8, 2010 6:40 AM
    It is pretty logical to go the X58 route if you are planning for more than 2 cards...
    Only 2x HD 5970s would have significant bottleneck with x8x8 config of the P55...for rest of the cards, the x8x8 still would suffice...
  • 10 Hide
    jsc , January 8, 2010 6:49 AM
    For most of us, it looks like the P55 is the way to go for a gaming machine. I was a little surprised at how well two X8 channels did.
Other Comments
  • 9 Hide
    kirvinb , January 8, 2010 5:40 AM
    I wonder does the same go for 790gx vs fx
  • -4 Hide
    gilbertfh , January 8, 2010 6:19 AM
    I just ordered myself an ASUS P7P55D-Pro and didn't understand the difference... If I spent $1200 on video cards to go in this bad boy expecting it to test at higher performance that I will never be able to see by the naked eye it may have been a bigger deal(but it isn't).
  • 16 Hide
    gkay09 , January 8, 2010 6:40 AM
    It is pretty logical to go the X58 route if you are planning for more than 2 cards...
    Only 2x HD 5970s would have significant bottleneck with x8x8 config of the P55...for rest of the cards, the x8x8 still would suffice...
  • 10 Hide
    jsc , January 8, 2010 6:49 AM
    For most of us, it looks like the P55 is the way to go for a gaming machine. I was a little surprised at how well two X8 channels did.
  • 0 Hide
    neiroatopelcc , January 8, 2010 7:00 AM
    Does it make a difference for the motherboard wether or not all slots are populated when we talk energy? Each pcie plug is supposedly able to deliver 75W to the cards right? so at 3 cards that's quite a bit of power. In addition it has to deliver what, 140W? to the 4ghz cpu .... remembering an earlier article detailing failed boards because of inadequate vrm's I just have to wonder if a higher power draw on the pcie connectors would make a difference in sustainability with such an oc? I mean at some point I would assume a board can draw more power than the atx connector or the power plane can handle?
  • -7 Hide
    a4mula , January 8, 2010 8:02 AM
    pcie 2.0 supports up to 300w (1.1 was 75w). The 5870 draws about 170w at load. This was the reason the 5970 was scaled back to 5850 speeds. Overclocked 920 @ 4.0 is going to draw about 250w. i5 750 (@ 4.0) on the other hand draws about 150w.

    For awhile now it's been known that the p55 will run an 8x8x crossfire within close proximity of it's x58 16x/16x even on 5870's. The only real question that hasn't been seen is the quadfire 5970's and a trifire 5970+5870. Publish that and you'll garner my attention at least.
  • 0 Hide
    neiroatopelcc , January 8, 2010 8:45 AM
    300w ? but why then would new cards still ship with pcie6 and 8 connectors if the cards actually could make do with the pcie supplied power? I mean, sure for pcie1 support, but won't they still bitch if one was to not plug em in under pcie2?

    ps. 150W is also a lot for a processor designed for two digit numbers. Is there some kind of list somewhere of which motherboards support how much vrm power, or how many phases generate how much wattage or whatever can be used as a guideline?

    Gonna upgrade the p35 to p55, and I've never been one for stock speeds...
  • 1 Hide
    jennyh , January 8, 2010 9:33 AM
    The gap is just going to increase with more and more powerful graphics cards. We're talking 1-2 years and 8x will be performing just like 4x is now.

    8x Pci-e lanes should now be considered a drawback when purchasing new hardware.
  • 8 Hide
    notty22 , January 8, 2010 10:39 AM
    "8x Pci-e lanes should now be considered a drawback when purchasing new hardware."


    They just proved it was NOT a drawback with two 400 dollar top tier gpu's.
    Someone that advocates not upgrading the rest of their motherboard specs to the current high performance components such as DDR3 and the fastest hypertransport speed should not worry about THEORETICAL pci-e bandwidth.
  • 2 Hide
    baracubra , January 8, 2010 11:11 AM
    Yeaaaaah! I've been waiting for this article for quite a while now, this clears up a lot of speculation! I hope you guys do a follow-up article to test whether two 8x,8x are enough to support 2x 5970's....

    If this article had come out 2 weeks ago, I would have upgraded to an i7-870 and 2x 5870's, but now that we know Fermi is arriving in Q1 2010 I'm afraid i'm gonna have to wait. . . again -.-

    Oh well, that's why we love the PC market, always advancing :) 
  • 0 Hide
    Onus , January 8, 2010 11:15 AM
    "A slow DMI interface linking the CPU to the P55 Express PCH at PCIe x4 bandwidth certainly doesn’t help bolster the platform’s performance credentials, causing many to question why Intel would add the Core i7-870—a $540 part—as one of only three launch-day Lynnfield processors. Certainly nobody would drop such an expensive component ontp a “mainstream” motherboard. But that was exactly the option Intel was hoping many builders would choose."

    I'm sorry, but these statements were lame. Plenty of NON-GAMERS might want the CPU power of i7 without caring a rat's kazoo about graphics. P55 makes perfect sense for a number-crunching scientific workstation.
  • -9 Hide
    lradunovic77 , January 8, 2010 11:20 AM
    P55 is waste of money.
  • 2 Hide
    JohnnyLucky , January 8, 2010 11:22 AM
    Just read the article twice trying to digest the benchmarks. I have to keep reminding myself that it is aimed at high end gamers and enthusiasts. I'm guessing the typical gamer uses only one video card.

    I'd like to see a new article about video cards for high end mainstream use such as professional digital imaging, video editing, graphics design, and engineering.
  • 1 Hide
    neiroatopelcc , January 8, 2010 11:22 AM
    jtt283I'm sorry, but these statements were lame. Plenty of NON-GAMERS might want the CPU power of i7 without caring a rat's kazoo about graphics. P55 makes perfect sense for a number-crunching scientific workstation.


    True - and for image editing as well. Built an i5-750/P55 system before xmas specificly for use with raw 10mpixel images and such work. Don't think the 4350 card I put in the system matters much for its purpose, and a 5870 would've made it the system worse in fact, as we needed the hdmi plug :) 
  • -2 Hide
    neiroatopelcc , January 8, 2010 11:22 AM
    lradunovic77P55 is waste of money.

    explain
  • -2 Hide
    fozzie76 , January 8, 2010 11:45 AM
    Please test the ASUS P7P55 WS. It uses the NF200 to offer true 16x/16x slots on an 1156 board. I may be buying it with my tax return. NewEgg has them in stock right now.
  • 0 Hide
    grillz9909 , January 8, 2010 12:09 PM
    Good article! It helps clear some things up for anyone in doubt about purchasing a p55 setup.
  • 3 Hide
    cyberkuberiah , January 8, 2010 12:15 PM
    if u consider p55 with powerful single gpu's , there is no need for x58 .
  • 0 Hide
    roofus , January 8, 2010 12:20 PM
    There are only 2, maybe 3 cards that can saturate the full 8x bandwidth and I don't see that trend going the other way in a year, probably not 2 years.
  • 1 Hide
    h83 , January 8, 2010 1:05 PM

    For me it´s very clear, people who want to use 2 or 3 GPUs, should buy an X58 platform, the others, just go for the P55 or stick with the P45 or 790GX/FX.

    Just my opinion of course.
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