HD 3850s in Crossfire - no improvment in performance any suggestions?

Before anyone starts - I know crosffire is problematic and I know it isn't always better than a single card set up but ---

I have recently installed 2 HD 3850s on my Asus Formula mobo. However I'm not getting any improvement in performance under crossfire over just running one HD3850. I am using CCC 7.11, no problems with the image plays games OK runs 3DMark06, no device conflicts shown, both cards are displayed in device manager. No problems with CCC I can see. GPUZ shows CF active. But the scores I am getting in 3DMark06 are the same for the two cards installed, two cards running under CF or even the same if I disable one of the cards.

I removed the old drivers and CCC for my previous card before installing these new ones and used the most recent CCC. I've already tried reinstalling the drivers but no change.

My PSU is rated for 2 graphics cards. All drivers are the most recent except my BIOS which is the original (although obviously not old) - I am waiting on a reply from Asus to see if it could be a BIOS problem but this doesn't seem likley as the board is rated for CF out of the box.

The only thing that seems odd is that in device manager i see both cards but not the second line that I saw with my old X1950XT which said something like "secondary ATI 1950X etc etc".

Has anyone had the same problem or can anyone suggest anything else I can try?

If it helps my system specs are:-
Asus formula specials edition
E6750 OCed to 3.4GHz 425MHz FSB
2 x 1Gb Geil DDR2-800
OCZ GAmes X Stream 600W PSU
2 x HD3850 256Mb
2 WD 320Gb Caviars in RAID1
7 answers Last reply
More about 3850s crossfire improvment performance suggestions
  1. I know personally that if you have any of the 3D options in CCC set to anything other than 'Use Application Settings' you will get low 3DMark scores ie. My old X1900XTX with all settings in CCC for 'Quality' would only get 30FPS in 3DMark03. When everything is set to 'high performance' & 'Use Application Settings' I would then get 4-5 times for FPS. CCC is very good at making graphically advanced games look even better but for benching you need to turn all the gubbins off.
  2. Quote:
    The only thing that seems odd is that in device manager i see both cards but not the second line that I saw with my old X1950XT which said something like "secondary ATI 1950X etc etc".
    Did you have two 1950's in crossfire? If not, I believe that the secondary is for additional displays (more than one output on the back of the card). I have seen this on a few work computers around here and that's the best determination I can come up with.

    Also - What res are you running the 3850's at vs. your 1950?

    I'd try closed_deal's suggestion and see if that helps.
  3. No it was just a single 1950. Maybe your right the secondary was part of hydravision or whatever its called to support another monitor.

    Same res for the 3850s and the old 1950 - 1280 by 1024.

    i'll give it a go leter.
    I was also going to uninstall allthe drivers and CCC and install CCC 7.10 - from other forums it seems that CF set ups can work better with different versions. Also the benchmark tests on sites i used to chose the 3850 were using 7.10 so hopefull it will work for me if it worked for them???
  4. which os are u using? If it is Vista maybe you will need some patches, I forget the numbers of them though.
  5. Somethign is goofy, I'd check out the xtremesystems forums. Lots of ppl over there have the 3850 and 3870 crossfired and oc'd so you would prolly have better luck finding the right settings, bios, windows updates, etc., checking those threads out.
  6. I just installed a 3870. I am disappointed in the FPS, I got about the same FPS on my old 7600GT at the same settings. I thought it would be more at low settings.
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