6850 Crossfire still doesn't work

A few months ago I had a thread on here because I found that my 6850s in Crofssfire were negative scaling on just about everything. Back then we came to the conclusion that my processor, the AMD Athlon II X4 635 was to blame because it wasn't powerful enough to feed both of the cards.
However, I recently helped a friend of mine rebuild his computer and in return he gave me some money and his old processor. The processor is an AMD Phenom II 550BE. It successfully unlocks to a quad core and I currently run it at 3.6GHz. It is significantly more powerful than my old Athlon. However I'm disappointed to find that the result is the same, negative scaling on every game. It only seems to work well on the Heaven benchmark.

I have tried everything I can think of, just yesterday I used Atiman Uninstaller to rid my system of EVERYTHING to do with ATI & AMD and reinstalled the latest driver and cap, all to no avail. I'm getting tired of it not working and I'm really in desperate need of help.

Thank You,

CPU - AMD Phenom 550BE UNLOCKED and OCed to 3.6GHz
MOBO - ASRock M3A770DE
Graphics - 2x Gigsbyte Radeon HD6850
PSU - Coolermaster 650w
RAM - 2x 2GB Kingston HyperX 1333MHz
60 answers Last reply
More about 6850 crossfire doesn work
  1. I'm going to go with board, perhaps PSU. Your board does 16x/4x CF, so you basically have two cards in 4x mode. CF should work, but not very well.

    Which CM PSU? They have some duds so perhaps your cards don't have enough power? CF bridge is on? Enabled in drivers? Testing with games that support CF?
  2. I didn't think that running in 4x mode would be that significant. The PSU I'm using is this one http://www.coolermaster.com/product.php?product_id=5924 CF Bridge is one, maybe a silly question, but does it matter which way round the bridge is on? It's enabled and I've tried it on all the games I own, most of which should benefit from crossfire.
  3. Anyone ? :)
  4. i'm a total newb when it comes to multi-gpu setups, but what about the CF bridge itself?
  5. Well I've tried 3 different bridges and the result is the same. So I doubt that's the problem, but thanks
  6. You didn't indicate what games you are playing, how many FPS do you have ? at what resolution ?
  7. I Know For A Fact That Is Not Your CPU, A Friend Of Mine As An Athlon 64 X2 6400+ @ 3.2GHz And 2 GT275s SLI And Is Having No Problems What So Ever, The Problem Is That You Shoud Never Run Mutiple Cards Below x8 PCI-E
  8. Sorry for not making it more clear. I run games at 1920x1080. The games I have tested include F1 2011, Crysis 2, Battlefield 3 and DiRT 3.

    On F1 2011 with the benchmark I get:
    Avg - 53FPS (No Crossfire)
    Avg - 47FPS (With Crossfire)

    On Crysis 2 I get:
    Around 50 - 60FPS (No Crossfire)
    Around 15-30 (With Crossfire)

    Battlefield 3:
    Around 50 - 65FPS (No Crossfire, Everything Medium)
    Around 20 - 30FPS (With Crossfire, Everything Medium)
  9. hella-d said:
    I Know For A Fact That Is Not Your CPU, A Friend Of Mine As An Athlon 64 X2 6400+ @ 3.2GHz And 2 GT275s SLI And Is Having No Problems What So Ever, The Problem Is That You Shoud Never Run Mutiple Cards Below x8 PCI-E

    Really! That's awesome. I knew there was a loss of performance when running cards at x8 and x4 but I always thought it would only be 5-10%. Problem is, I know nobody who has dual 16x or 8x motherboard so I can't test my graphics cards on another motherboard.
  10. I've read that the drop off for using one of the latest cards in a 4x slot is like 25%, but I doubt it would be that high for a 6850.

    I would use MSI Afterburner to see what your GPU's are actually doing. Maybe you could try a fresh install, I just switched an Nvidia for an AMD card and the driver would not load right no matter what I did. I did a fresh install it worked properly, AMD drivers seem to be finicky sometimes.

    I have never heard of actually getting negative scaling from a 4x slot.
  11. I used Atiman Uninstaller to rid my system of graphics drivers and installed the latest ones. I did this twice and crossfire still doesn't scale properly. I will have a look at GPU utilisation at some point tonight and get back to you.
  12. Okay, I've done some tests on the GPU Utilisation in Crossfire. When playing F1 2011 my primary card runs at about 50% and my secondary runs at about 80-90%. The processor was running between 65 and 75%.

    Maybe this indicates that the secondary card is using almost all the bandwidth it can get from the PCIE x4 slot and the primary card has to slow down to stay in sync with the slower card?

    I doubt I'm 100% correct but that seems quite likely?

  13. Get GPU-Z if it tells ur its enabled then u are also on crossfire x16 x4 can be a huge significance, because if its x16 x4 its almost useless to have two cards one's running at x16 which means for crysis 2 50-60 fps like u said, but the 2nd is only x4 so it makes it considerably weaker
    x16x16= 93-97% efficiency
    x8x8= 83-91% efficiency
    x16x4=71-80% efficiency
    and these are for gpu supportive games some might even go below 50% but crysis 2 is not one of those games.

    although the FPS shown here means that the FPS still should go up by quite a bit, it could be a problem where one of you're cards is defective, u should try switching around the cards and if it still 50-60 fps with each individual cards it's possible you're motherboard is malfunctioning and it's hurting another video cards fps or something and only the x16 slot works, u should try getting a new mobo or burrow one and see the results.
    i have the same 6850 crossfire and cpu
    i also have the Gigabyte FXa-ud3 which has x16x16 for about 150$.
  14. I am not sure but could 2 x 2gb 1333 ram pose as a bottleneck for a crossfire situation?

    also are you installing BOTH the full Catalyst Software Suite AND the seperate link for the ATI Catalyst Application Profiles on the AMD driver page?

    Even if you are running at 4x it shouldn't really decrease performance....
  15. Yep, I've got both the latest drivers and cap. I don't think the ram should act as a bottleneck, both the speed and capacity is pretty good
  16. I suggest trying the following single card experiments:
    try each of the Single Cards in each of your slots, so Card A in the 16x slot and 4x slot, then Card B in the 16x slot and the 4x slot (so 4 tests). Run a consistent benchmark like unigine, or if you have crysis use the benchmark tool, or games with benchmark tool include: arkham asylum, res evil, far cry 2, metro2033, dirt 2 and 3

    This will let you compare Card A to Card B AND the two PCI-E Slots to each other.

    This would conclude whether for example one card is defective, or if one of your slots is either defective or the 4x slot is actually really slowing you down.
  17. ^+1

    Best to do it as amirp said , its the only way you can narrow down the problem to your situation.
  18. I just said what amirp said xD b4
  19. Lol true... but I repeat it for clarification and the fact that he has to do those tests I (we) mentioned to rule out a bunch of critical stuff
  20. Thanks guys, I will do the test after I get back from school today and post my findings
  21. I've done the tests. I get pretty much the same results on both cards and on both the x16 and x4 slots. The x4 slot results in about a 1FPS decrease, that's it. I can't think of anything else that could be causing the problem.
  22. I hate to be like this... but, i think it's still your CPU.

    The 550BE is a weak cpu. You may have it overclocked, but your problem is cache. You need cache to have better transfer between your GPU; CPU; and ram.

    I'm pretty sure this is what is messing you up. It may be able to run two 275s - but the 275 is not a processor hungry "modern" card.

    The 6850 is also known for being risky in crossfire. I would suggest a new CPU and MOBO. This will most likely solve your problem!
  23. It's unlocked to a quad core as well however, which means the performance right now is closer to a Phenom II X4 965 than anything else (it also has the same cache) and from what I've seen a X4 965 is perfectly capable of running the 6850s in crossfire.
  24. I don't think its a CPU issue. If it can do two 275s, then the 6850 isn't a problem either seeing as the GTX275/280/460 and 6850 all have very similar performance. Difference is in power use and DX levels. Not sure what you mean by "risky" so I'll ignore that.

    Any update on the PSU? Try other CF bridges yet? Update drivers or CAP? (the application profile things.)
  25. I've tried 3 crossfire bridges, can't get hold of any more, performance is the same with all of them. Running an absolute fresh install of AMD Vision 11.11 with the latest CAP.

    I have tried both cards on both PCI E slots, and performance is much the same throughout.

    How'd you mean with my PSU? I'm pretty sure its working fine as it's a good quality one.

  26. tjcoops said:
    It's unlocked to a quad core as well however, which means the performance right now is closer to a Phenom II X4 965 than anything else (it also has the same cache) and from what I've seen a X4 965 is perfectly capable of running the 6850s in crossfire.

    Not the same architecture though...
    Which is why the 2500k beats all of amd's quad cores. (Even though they have the same amount of cache).

    Like i said also. It's your MoBo too; the 6850's are infamous for having troubles with crossfire. Yes it has been successful - but with higher end motherboards.
    Yours on the other hand, is an Asrock that was 60$$... Which means lowend parts - which Equals bad chipset's.

    I'm not saying this is the problem. But with both of your cards working it's the only thing i can think of!
  27. Exactly, even with the weak processor, I should still see some improvement, albeit a smaller one than if I was using an i5 or a bulldozer but the motherboard is the only thing I can see that can bring such bad performance.
  28. It's the motherboards fault because it cost $60? Bad chipset? They are all the same now...

    Have you tried removing the OC? What if you leave the OC but lock the cores back up? Perhaps something isn't stable on your CPU side.
  29. I'll try that soon and get back
  30. yes, now it's time to rule out your CPU, try bringing it back to full stock (dual-core) and run the tests. If you see improvements then it was the CPU. If it gets even worse or stays the same I'd would then say get a new motherboard unfortunately.

    Just for completions sake tho, what is the exact model of your power supply unit?
    It may be unable to produce enough power.

    Also when both cards are in, do you have the proper PCI-E cables connected to the cards, or are you using Molex-6 pin converters. Not sure how true this is but if you use more than one on the same card that's probably not good.
  31. I've asked for it several times already, he isn't saying.

    It's probably ok. Two 130W GPUs, a 125W(?) CPU and my usual 50W for rest of system means he's drawing around 450W(ish). I realize its a CM, but its still a 650W PSU. I/he hopes.
  32. Sorry for not replying, I've been flashing ROMs on my phone all night :P My PSU is the CM RP-650-PCAP.

    I'll check over the CPU tomorrow. Night
  33. According to this its a 30A unit.


    30A * 12V = 360W.

    Assuming this is true, you're stressing the crap of the PSU and it doesn't really have enough power for what you want. Taking another look online I do see that its supposed to have two 12V rails rated at 18A together. Even if you assume it can do 18A at the same time on both rails (HUGE ASSumption.) that's still only 432W. As I said in my post previous to this you need around 450W for two 6850s, you are short on power. Probably explains why one card is ok, but two cards suck.
  34. tjcoops said:
    Really! That's awesome. I knew there was a loss of performance when running cards at x8 and x4 but I always thought it would only be 5-10%. Problem is, I know nobody who has dual 16x or 8x motherboard so I can't test my graphics cards on another motherboard.

    You're right...

    if your running X16 x4 you can't have anything else plugged into any of the PCIe or PCI slots... if you do the cards will split the bandwidth thus effectively eliminating CF. It won't work at X16 X2 if you know what I mean. If this isn't the case, have you checked each card individually?
  35. @4745454b you're right and I agree with you. OP you need a new power supply to run your computer in crossfire, that thing is a piece of crap lol... sorry.... and for now run with only one card so you dont damage your system.
    This is it right:?

    Im not sayint to buy this.... but even this 520watt antec PSU is producing more power

    I would buy something along the lines of this:
  36. I get the feeling someone is going to be very upset when he wakes up....
  37. LOL better upset than computer explodes....
  38. Didn't realise it was quite that bad :P that's really terrible, I'd looked at some reviews of it and they (customers) said it wasn't too bad. Wow, I'll take my graphics card to my friend and test them there, he's got the same motherboard as well.

    Thank you guys ever so much, I wouldn't have thought my power supply could have been the problem. No doubt I'd get a lovely new motherboard for Christmas, get it all set up and things would be exactly the same.

    You guys have saved my christmas present from being a let down :P

    Thank you all
  39. If you can test it on a same motherboard but better PSU, I'd love to see the results. If the problem is fixed, might just bookmark this thread so others can read about what happens when a system doesn't get enough power.
  40. Thanks, it will be interesting to find out. So I'm looking for a power supply with higher current? :P sorry, I've never really looked into them enough to know, so it serves me right for having a crappy one :P

  41. I'm not sure how I want to reply to this post. Higher 12V current is one thing to look for yes. Efficiency is another. OEM is another. Total wattage is another. There are many things to look for. You might just want to post in here what PSU you are thinking of getting.

    PSUs made by Seasonic, Delta, CWT, and Eneramx are usually considered the best. There are others, but this should get you started. These sell under their own name, or others such as Antec, Corsair, XFX, etc. Get something with PFC, and is 80+ bronze or better.
  42. Currently using my Dads OCZ GameXstream 1010W PSU, as far as I can tell there's no difference. In some games FRAPs registers the game running at 80FPS or 100FPS for example but in all honesty it looks like its running at 20 or 30FPS.
  43. Suffering from microstuttering then? Or perhaps some issue with Vsync.
  44. In F1 2011, theres still negative scaling. I'll do more tests in the morning :)
  45. have you tried bringing your CPU and bios settings all down to stock settings?
  46. I haven't tried that yet. I won't have this PSU for much longer as Dad wants it back :P Just an update though, I've tested 3 games, F1 2011, Battlefield 3 and Medal of Honor (2010). F1 2011 is still terrible, averages 37FPS. Battlefield 3 is now running on a mixture of High and Ultra settings and I get a solid 60FPS (Vsync) and it looks lovely and smooth, however it doesnt run nice without VSync. Medal of Honor is running at the highest settings with 8x AA and I get between 120 and 180FPS.

    Some games seem to be running pretty damn nicely! :D I know my motherboard isn't the best for crossfire but I can now safely say that my power supply is the biggest problem. Christmas Present seems to be sorted (Power Supply if you didn't guess) :D
  47. Have you checked the temps of the cards? Maybe one/both is getting hot? Might want to check the temp of the CPU if you haven't already.
  48. The Maximum both the cards get to on F1 2011 is 60c, which is fine? My processor core temperatures are disabled because it's unlocked, however on HWMonitor my CPUTIN temperature reaches a max of 40c which is also fine I think, and I've heard that the CPUTIN temp is higher than the actual core temperatures.

    Did notice that the PSU's 12v runs at 13.33v when idling and drops to 13.18v under load, however that's according to HWMonitor and apparently software voltage monitoring is inaccurate so it could be fine.
  49. CPU temp looks off unless you have exotic cooling. 40c under load is way to small.
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