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Graphics 6950 or 2x 4870 crossfire / other questions about new build

Discussion in 'Hardware' started by Andrew K, 28 Mar 2012.

  1. Andrew K

    Andrew K What's a Dremel?

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    Hi I'm currently upgrading from an older PC, the only thing that might be worth keeping is the radeon 4870. I'm thinking about keeping the 4870 and buying another one versus the option of just getting a new 6950.

    I know you'll tell me the 6950 is better then two 4870. But would it be big improvement? The cost difference is substantial.

    Second question is the power req. Is a branded 650watt psu going to be enough for 2x4870 ?

    Third and last: The 6950's... can they be crossfired? I mean they are already built with like two units... If I ever wanted to upgrade in future would another 6950 be an option and should I consider special mobos with that in mind? Mobos that have enough room between pci-e slots?
    thanks
     
    Last edited: 28 Mar 2012
  2. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    6950. 4870s are too old now to carry forward. Also, no dx11 features with 4870s. And the power usage from two versus one card is substantial. And then there's the whole CrossFire scaling issues of the older generations of cards. And you're more likely to hit the vRAM limit with 512mb/1GB cards than you are with a 2GB card.

    Second question: Yes, but you're not going for two 4870s ;)

    Yes 6950s can be crossfired. Not sure what you mean by being built with two units. They're still only single GPU. CrossFire scaling for the 6xxx series is very good. I'd certainly look into a board that does at least 8x/8x CrossFire.
     
    Last edited: 28 Mar 2012
  3. Parge

    Parge the worst Super Moderator

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    Definitely a 6950, much quieter, has DX11, 2GB or vRAM (assuming it’s the 2GB version), plus you won’t be reliant on Crossfire drivers to make your games run at a decent pace.
     
  4. mars-bar-man

    mars-bar-man Side bewb.

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    Just to add another spanner in your 4870 plan, I had 2 of them a while ago. I think my 750w PSU just about coped. I wouldn't be happy running them off a 650w.

    The 6950 will be a much better card.
     
  5. dunx

    dunx ITX is where it's at !

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    Ideally you would use a MoBo with a spare slot between the two 16x/8x PCI-E slots to aid cooling...

    HTH

    dunx
     
  6. Andrew K

    Andrew K What's a Dremel?

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    yeah, thats what I thought... thanks for all the replies.

    I have to admit I've had issues with my 4870 overheating... and its noisy.

    As for 6950... I assume you dont need two 6950's of identical brand? Could you crossfire two 6950 of different makes? Or even one 1gb one and one 2gb one? How about crossing 6950 with a 6870 ? I'm curious because I have no experience in crossfire/sli.

    Also there are mobos that can take triple or quad gpu right?
    With my future proofing in mind should I get one of these? Or is this an overkill ?
     
  7. mars-bar-man

    mars-bar-man Side bewb.

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    You can link up pretty much any AMD card as long as it's from the same generation, so a 6950 would work with a 6970 and/or a 6990, pretty much any config.

    And there's plenty of mobo's that can support Quad-Fire, just look for a board that has 2 or more PCI-E slots. Most boards come with them these days.
     
  8. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    Quad Gpu from any brand is total overkill and often gets worse performance than tri due to poor driver support. Getting tri GPU on 1155 (I assume you'll be going for this) isn't the easiest thing. It requires the board vendor to use an NF200 chip to add more PCI-E lanes so it adds a fair bit of expense. (Unless you use a gual GPU card)

    You can't CrossFire a 6950 with a 6870 as they're based on different GPUs. 1GB with 2GB would work but you'd be limited by the 1GB card. Identical branding isn't necessary, identical GPU is. And try to get the same clocked cards as it just makes life easier.
     
  9. mars-bar-man

    mars-bar-man Side bewb.

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    I'm sure you could, I might be wrong (probably am, not had an AMD card since the 4xxx series), but I thought you were able to link to cards like that up?
     
  10. Andrew K

    Andrew K What's a Dremel?

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    yeah this sounds like a good idea. adding another 6950 or two when the prices drop etc.

    Btw is it just me or is this official that there are a lot of boards that DO support radeons cf but DON'T support nvidia's sli?
     
  11. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    Cards like the 6950 and 6870? As far as I'm aware (and I'm very open to being wrong) a GPU must be within the same series such as 69xx or 68xx. You can't mix the two without something like the Lucid Hydra chip in between doing some negotiating.

    And yes you're correct Andrew K. Reason being that for SLI boards have to have at least 8x/8x split between two PCI-E slots to be able to get SLI capable branding. Whereas CrossFire ready branding only requires 16x/4x split, which most boards do. This doesn't mean it's good idea though. 4x bandwidth is crippling for higher end GPUs.
     
  12. rollo

    rollo Modder

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    You don't even need same speed cards

    They clock down to lowest unless you tell it not too
     
  13. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    True, but why buy an OC card then add a non OC card? Might as well get two that run at the same speed out of the box.
     
  14. Andrew K

    Andrew K What's a Dremel?

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    ok so same underlying chip but the weaker one is the limit...

    so lets say i get 6850 and then later on i decide to buy a 6870.. am i wasting money and should buy another 6850 instead? is that how it works?
     
  15. mars-bar-man

    mars-bar-man Side bewb.

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    Pretty much! You could try and OC the 6850 to 6870 speeds, but it's no guarantee that it'll make it.
     
  16. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    Pretty much, you'll always be limited by the weaker card. So a bit pointless (unless you get a good deal) on buying a higher end card. I'd always recommend going for two of the same anyway (6850+6850 etc) purely because then you have 100% certainty all will be fine. CrossFire drivers are sometimes a bit naff so mixing different cards may make things worse.

    Edit: Bloody ninja mars-bar-man lol

    Edit 2: Also worth pointing out the core count difference between 6870 and 6850, another limiting factor.
     
  17. Andrew K

    Andrew K What's a Dremel?

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    thx, so i'm currently thinking about something like that:

    Asus M5A97, AMD 970, S AM3+, DDR3, SATA III - 6Gb/s, USB3
    AMD FX 4100 Black Edition, 3.6GHz OC'ed to 4GHz
    Arctic Cooling Freezer 13 CPU Cooler8GB
    (2x4GB) Corsair, DDR3 1600MHz
    2GB ScanFX HD 6950, 800Mhz GPU, 1408 SPs, 5000Mhz GDDR5
    600W Corsair Gamer Series PSU (enough???)
    2TB Seagate Barracuda, SATA 6Gb/s, 7200rpm, 64MB Cache

    any critique?

    in the mobo specs , when it says that a certain ram frequency is only available by overclocking "DDR3 2133(O.C.)/1866/1600/1333/1066" is this an issue? OCing ram?

    This particular borad has:
    1 x PCIe 2.0 x16 (blue)
    1 x PCIe 2.0 x16 (x4 mode, black)

    which means one is x16 and one x4 when i do crossfire right? Am I reading this right?

    In which case if I put two 6950's in , is this crippling the potential?
    Noizadaemon said that "4x bandwidth is crippling for higher end GPUs." , and I assume 6950 can be classed as such?

    Should I really look for a double pcie x16 mobo or am I ok with that one, or maybe am I just misreading these specs?

    thanks
     
  18. rollo

    rollo Modder

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    because you can overclock the card yourself in 90% of all cases to the same speed
     
  19. noizdaemon666

    noizdaemon666 I'm Od, Therefore I Pwn

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    Nice spec :thumb: Personally hate the FX 4100 but still a decent chip.

    600W is more than enough for that system.

    You won't be overclocking the RAM, you'll be overclocking the FSB or whatever it is called now on AMD to achieve the RAM speed. Basically the FSB is multiplied X times to get a RAM speed.

    And yeah, I wouldn't bother even trying to CrossFire a 6950 on a 4x bandwidth slot, it's too limiting. Ideally you need 8x/8x or above.

    It depends whether you think you will crossfire or not as to whether you need a different board. I'd personally always get a board with the option of more than one GPU just so future GPU upgrades are less expensive. However, adding a second 6950 will more than likely warrant a PSU upgrade as well.

    Edit: Rollo, yes you could do that, but what happens if you're part of the 1% who end up with a GPU that can't overclock?
     
  20. Andrew K

    Andrew K What's a Dremel?

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    yeah , i'll go and look for another mobo, one that can do 8x,8x or above.
    What wattage should be enought for two 6950 ? 700? 800?

    i want to upgrade with SSD and second 6950 some time in future, on my next upgrade checkpoint
     

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