Crossfire HD5670 in x16x4 configuration


First of all, I'm generally not that much into hardware so maybe my question will sound a little bit stupid.

I have recently bought myself a shiny new computer targeted mostly for working but at the same time I wanted to be able to have a good gaming performance at a reasonable price. Components:

MSI 870A-G54 with an AMD Athlon II X4 640 @ 3 Ghz
MSI ATI Radeon HD5670 1GB
4 GB DDR3 Ram.

I was really suprised by the low price of about 300 € and the good perfomanced with games on my old CRT screen running @ 1024x768. Now I recieved a very nice christmas present, a huge 24'' LCD running at 1920x1080 and my gaming experience lost a little bit of its gloss so I came up with the idea of buying another graphics card and run it in crossfire mode.

Sadly my retailer doesn't offer my original MSI card at the moment and so I would have to go for a ASUS EAH5670 1 GB RAM. From what I've read in the Crossfire Guides having cards of differnt brands shouldn't be a big deal, am I right?

Another concern is that my motherboard isn't adequate for running in crossfire mode (even though it was advertised as being). The problem is that it has 2 PCI Express x16 slots, one running at x16 speed, the other one is only wired for x4 speed. In the Crossfire/SLI guide is written that this configuration might not perform as expected so I would like to know what you think. From what I've also heard it gets better if both cards are running in PCI-E 2.0 mode, but does that apply for my cards too (because they are specified as PCI-E 2.1 cards).

Would you recommend me buying that ASUS card or am I better off buying a completly new card (eventually you also have got a hint for me on that -- power supply won't be a problem).

Thank you very much for reading until hear and helping me to make a good decision.

Another thing that came just up to me: Will I need a crossfire connector cable for this setup, because there wasn't one included neither with my motherboard nor with the graphics card if I remember correctly.
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  1. As long as the cards are both 1gb and ddr5 there shouldn't be any problem with them being different brands.

    According to MSI itself and reviews on the net, If you put a single card in the first slot it'll run at full x16 speed, but if you put it on the second slot it'll run at x4. Now if both slots are populated both cards will run at x8/x8, meaning there'll be no performance hit at all, even a 5870 only suffers 2-3% less performance from running on x8 mode, only dual cards like a 5970 have a noticeable impact on performance out of that.

    On a motherboard with PCIE 2.0 slots ALL slots will be 2.0, there are o motherboards with mix-ups like that, PCIE2.1 is just a stepping before PCIE 3.0, don't know what the advantages are or if there's any advantage at all other than it gives incompatibility problems for people with first-gen PCIE mobos, but you'll be fine using that motherboard.

    And yes you will need a crossfire bridge to connect the 2 cards
  2. Thanks for the quick response.
    Both cards are 1gb and ddr5 so that won't be a problem then.

    The reason why I'm a little worried about what you've written about x8/x8 is that in this review about the motherboard is stated:
    "[...] two full length PCIe x16 slots. Similar to Gigabyte's board, the secondary PCIe x16 port is only wired for x4 bandwidth, which means Crossfire is likely to suffer a performance hit when using this AMD 870 motherboard. "
    Maybe I missunderstand it (I'm not an English native), but if it's only "wired" for x4 bandwith how can it go to x8 speed? On the other hand 5670 is not a real high-end card so there might not be a need for x16 / x8?
  3. here:

    From Techradar UK: "Expansion slots include a pair of PCI-e x16 graphics ports, enabling multi-GPU CrossFireX gaming. Admittedly, you only get eight lanes per slot with both populated. But in our experience that's plenty for all but a pair of dual-GPU cards, such as the Radeon HD 5970"

    There's confusing info on that board, some say it will do x8/x8, others say one card will run at x16 while the other is at x4. But a higher amount of people agree to the second statement.

    Look at this comparison for the gtx480:

    There's a hit that could be calle noticeable in cases, but remember it will be ALOT less when using a 5670, It's definetly not a good motherboar for crossfire, but I'd say it's still worth it getting a second card you'll probably loose about 10% of the peformance it should have in the worst case, but the 90%+ improvement of crossfire will compensate for it
  4. Ok, thanks again. That means that I'll go and get my first multi GPU system :-)
  5. HOLD ON A SEC!. read my edited post.
  6. Oh, I didn't see your edit, thanks for the additonal post.

    Well I guess the impact wouldn't be too big, as you said the mobo is not really suited for crossfire but with the 5670 (which is way slower than a gtk480) this shouldn't be a show blocker.

    On the other hand I just found the HD 5770 quite attractive. It would cost me about 120 € (which is 40 € more than another 5670) but I could probably sell my HD 5670 for 50 € or something like that which would make the 5770 even cheaper than going for a crossfire system with the advantage of not having the usual multi GPU troubles, no problem with the mobo, less power consumption and less noise.

    Wouldn't that be even better, the 5770 would have about the same performance as two 5670, no?

    Ok, according to this review:, the perfomance of 2x 5670 and one 5770 is ~about~ the same. From what I've seen in the graphs sometimes they offer the same FPS, sometimes the crossfire system wins, and from the to time the 5770 is faster. So not a real help...

    This is way I hate having too many options and having to oughtweigh all different pros and cons....
  7. 5770 perfroms about on par with crossfire 5670, and if you sell your current 5670 It'd go for about the same as a second 5670, Without the potential driver issues, extra heat and the fact that not all games support CF/SLI, and no loss of performance because of the x4 slot . So it's definetly a better choice all around.
  8. Ok, I'll buy the 5770 then.

    A lot of thanks again, for giving me such a good expertise!
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