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CrossfireX - This possible, and any benefit?

Discussion in 'AMD / ATI' started by Formula350, Feb 8, 2010.

  1. Formula350

    Formula350 New Member

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    I know that there was some debate whether or not running both links in standard Crossfire, with some evidence to there being a slight gain in higher resolutions, but that got me to thinking about 3-way (or I suppose 4 as well) CF-X... Hate to link to another site for a pic, but it's the perfect example...
    [​IMG]

    If you were to grab a longer link (seen them on eBay) and connected up card 3 to 1, think the same gain could be had at higher res or with AA cranked up? Similarly you could connect up cards 1-4 in a 4-way CF-X setup. While I sadly will not have the funds ANYTIME soon to do something like this, and the planned upgrade won't even have a mobo capable of doing more than standard CF, I just feel like if no one ever asks then no one may bother to try. Or perhaps also that no one may even have thought of it, but surely that couldn't be the case :p

    So anyone know? Or willing to give it a go, for any of those lucky enough to be running a tri-card config? :)
  2. cadaveca

    cadaveca My name is Dave

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    No difference for me. Tested on 8x8x8, 3x 3870, and 3x 4870.

    You would think, the best would be connecting both lower cards to the main card...but I did not try this recently...now I'm sad I no long have the cards, nor the board, to try.

    It would have to be driver-dependant, one would think.


    :cry:

    What I did find...take two cards...one clocked slightly higher than the other...best result are with the higher-clocked card on top.
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  3. Formula350

    Formula350 New Member

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    Well ATi had said only one connector was required, but as the enthusiasts we are, we (well they haha) tried it anyhow, only to find minimal gain if any. Theorized it was due to the added connector providing a bit more bandwidth. Though I wouldn't be surprised if it was more the case of "finding the path of least resistance" over actual bandwidth gain. Not sure the exact roll the drivers play in regards to the interconnects though, so I can't even hazard a guess if it's needed or not.

    One thing I'd love to see someone manage, or if just the registry entry being turned on via regedit or ATT, would be allowing the G/GX mobos to Hybrid with any card :) That would take a bit more driver modification me thinks, given they CF w/o an interconnect at all. Or at the least give the onboard the option to either drive physics. As for what I was referring to with the registry entry, as it says in ATT (in the Advanced Registry Tweaks section): MVPUEnableHCF, which I took as Multiple VPU Enable Hybrid-CrossFire, but the more important option of MVPUForceHybridCF! I'm sure if I googled those two terms, I'd find what I"m looking for... but do I really want to rain on my own little parade? lol I have a feeling though, that it would be easier than we think, given the fact we can SoftMod with little effort.

    All I know, is I bought my nF4 board because I was taken by it's performance and tuning abilities, but was ignorant to the fact you can't crossfire on em >_< Irked my further when, whoever it was VoodooPC or someone, managed to hack a system to allow for it but were too chicken to release the drivers -_- If Ket is man enough to thumb his nose at Creative, I think they should've grown the chodes to release 'em :p So my next board will have the ability, as I plan to get a 5770 at some point, possibly just 2 if it's long enough and they are uber cheap. RELEASE THE DAMN RD890 ALREADY!!! >_< (Which, if anyone knows of their street date, PLEASE PM me!)
  4. cadaveca

    cadaveca My name is Dave

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    As to why it's driver dependent:

    How do slave cards know to push rendered frames out to the master card, and not jsut out the DVI Ports? And how do they know to use the bridge, or the pci-e bus, or DMI bus, for communication?

    It's all in the driver.


    ;)

    ATI says to connect BOTH bridges; it's board partners that say only one is needed. I know, for a fact, that I need two bridges @ 2560x1600, or weird things happen, but none will acknowledge this. Many say microstutter doesn't exist either, so take it all with a grain of salt.

    Oh, and my A8N SLI(NF4) runs Crossfire just fine, BTW. As well, the very first showings of Crossfire were on A8N NF4 boards. Nvidia rolled out a bios that prevented it from working shortly after.
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  5. Formula350

    Formula350 New Member

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    More proof of my ignorance of MVPU configurations heh I mean I knew there was driver work going on, but didn't really think about it enough to have thought about those situations.

    As far as crossfire working on that A8N... Would that mean if I were to go to an older BIOS on either my Gigabyte or DFI boards I could run Crossfire on them? The DFI one doesn't use the SO-DIMM card to turn on SLI, if that matters at all. Not that I have any money to get a second 1950 Pro, but it would certainly make me keep my eyes open for one lol
  6. cadaveca

    cadaveca My name is Dave

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    The best I can do to help you is point you to the HP/Voodoo Blackbird systems that use 790i boards for both SLi and Crossfire. It CAN be done... it's physically possible, but firmware/software stands in the way, due to liscencing.

    Just take a look at what happened to Uli...who had thier own chipset, bypassing the liscencing stuff, and that supported both Crossfire and SLi....nV bought them up quick!

    Also, INtel's P965 didn't support Crossfire until the bios was patched to configure the DMI bus correctly.

    But good luck getting it working...not likely with cards with internal Crossfire connectors, AFAIK....you need cards with the external dongles. But yes, bios is the issue preventing Crossfire on NV chipsets.
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  7. Formula350

    Formula350 New Member

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    Yea I think that was the same Voodoo who originally did it with the NF4, but before HP purchased them heh I thought it was all done through driver tricks though :\ Speaking of that... wonder what would happen if the BIOS on the video card was modified to reflect it's manufacturer and chipset ID as that of an nV card... I mean, other than having to modify the driver's if you ever were to update them, so it had those IDs point to what the card SHOULD've read lol

    Any idea what BIOS version would be the one to stay away from for that A8N? Buddy coincidentally has the A8N-SLI Deluxe :p

    My x1950 has the dual CF links like that in the picture above, so that's a start lol Not that I know how to code, which would at least give me a head start on being able to reverse engineer a BIOS :(
  8. cadaveca

    cadaveca My name is Dave

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    You might also have to hack the driver, I am unsure, as it's been some time since NF4 crossfire has been talked about.

    In all honesty, because of issues that may arise, it's really not worth the effort. ATi has issues with drivers still as it is, and they have many people working on drivers. Save yourself the headache and forget about it.
  9. Formula350

    Formula350 New Member

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    Well I more than likely won't bother with my rig, given that it's most likely nothing that is as easy as the A8N, being you've known it to. I only ask because my buddy has the A8N and he's constantly getting older hardware, either free or cheap, so him nabbing two cards wouldn't be to far fetched :)

    I mean, that's assuming that it'd work with an older BIOS and drivers (with maybe just some small inf tweaking needing to be done). He's typically the type who's more than happy to give silly stuff a try, after all, he went through the trouble building a PC whose sole purpose was to be the biggest POS around lol Got some horrible sound card that was basically like a "soft modem" not having any true hardware support, and then picked up one of the crappiest video cards we could track down which I think ended up being a Trident, all stuffed into a Cyrix based rig :p

    Anyways I appreciate all the info! Even if I don't have the right hardware, or current capability to accomplish modding what I do have, I can at least keep my eye open for some pre-modded drivers/BIOS since I now know it is more than just possible but fairly easy (in comparison to what I knew a few days ago which was it basically not being possible heh) :toast:
  10. cadaveca

    cadaveca My name is Dave

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    I wouldn't exactly call it easy...

    If you decide to venture down this road, let us know how it works out...if Voodoo can do it, so can anyone else with the programming know-how.
  11. Formula350

    Formula350 New Member

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    Other than an old BIOS for that A8N, you don't happen to know what else is needed do you? I've tried searching for info before, and I'm pretty good at digging up shite from google lol If a tweaked driver set is needed, and if there's info around somewhere about what needs work, I could at least attempt to modify some. Though I admit, my modding skills is only extended as far as the INF goes lol

    I'll let him know to keep his eyes open for some older cards ;)
  12. cadaveca

    cadaveca My name is Dave

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    You'll probably have to mod both the driver and the bios.

    And that's about all teh help I can be...some things just shouldn't be done, IMHO. 8x8 PCI-E 1.0 isn't exactly enough bandwidth for Crossfire.
  13. Formula350

    Formula350 New Member

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    Well that's the reason TO do it! Building a rig whose intent is to be a huge POS shouldn't be done either :laugh: And while he does have 1 3850 currently that he could do CF with, I was thinking more that era of card, such as 2 1900/1950s.

    The more you tell people not to, or that it shouldn't, the more interesting or desirable it becomes to do it lol Like nV's foolish move with the GF drivers refusing PhysX if another brand (or maybe it's just if ATi) card is present in the system. All that did was make people find a way around it :p

    Same reason I bought 2 of these behemoths!
    http://www.theburnerishot.com/photo/AAlchemy8164.jpg

    Not meant for consumer use, but damned if that'll stop us! :D
  14. cadaveca

    cadaveca My name is Dave

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    Yeah, you know, if I still had a working 939 cpu, I'd pop in some cards and see what happens with today's driver...you never know, it jsut might work without any fuss...

    And yuor point about overcoming a challenge is very astute...unfortunately, it's not something I personally find worthwhile. I just did this instead ;):

    [​IMG]

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  15. Formula350

    Formula350 New Member

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    LOL Well if I didn't want to hang on to my spare 939 I'd offer it up >_< Given, it's just a Venice, I'm tired of not having backup components heh

    And good lord, the more I see folks open-bench rigs (temp or not), the better I feel about mine LOL I suppose it'd only be fair to share how mine looks. My recent addition makes it look pretty dopey haha

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