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Two PCI-E cards - only one is recognised

Discussion in 'Building a new PC' started by kdn, Oct 8, 2013.

  1. kdn

    kdn Member

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    This was my setup: gigabyte motherboard: GA-970A-D3 with an AMD Raedon 6670 in PCIE slot 1. running DVI cable to monitor and HDMI cable to another big TV (extended display)

    That all worked fine.. then I went and built a flight simulator that sits next to the PC. The sim has two screens, one big HDMI TV and a small DVI monitor. So I went and purchased a second video card an AMD Raedon 7770. and put it in PCIE slot 2. Now when I first booted up the computer I could see both cards listed in the device manager. I did not have any monitors connected to the second hard at the time - so I thought good. I turned it off and finished the cabling only to find that now only the new card was working. Nothing changed inside the PC. The 7770 card is the only one that would display anything, I tried the VGA, the HDMI and the DVI of the 6670 but nothing would work. I removed the 7770 card and the 6670 worked just like it normally would. put the 7770 back in, and only the 7770 would work.

    I read the mobo manual, and was a bit upset, I found although the board has two PCIE 2.0 16x slots, the top one runs at 16x where as the bottom one only uns at 4x! so I thought it made sense to put the more powerful card into the 16x slot. after doing so, still the same issue, only the 7770 had anything on the display.

    In my bios I don't see any options for enabling or disabling the second slot. so I don't think its a bios issue, plus as I stated it did at one point work.

    So my question is how can I get both cards working at the same time?

    the only one thing I can think of is, I have a cooler master 500 PSU. and the system is an AM2+ 4100 bulldozer. one SSD, 2x HDD, 1x DVD, 2x 4GB RAM. According to my calculations I should only need 380watts, but could it be possible im underpowered to power up both video cards? the 6670 doesn't have an external power input, just motherboard, where as the 7770 has an external 12v connection. I am not sure though why the system would even start if it were underpowered and why the 7770 always get the power regardless of what slot it is in.
     
    Last edited: Oct 8, 2013
  2. sammorris

    sammorris Senior member

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    One card will always be the primary - that will usually be the one in the 16x slot. To get the second card doing anything useful you'll need to install drivers for it - so you'll need to run the AMD driver setup utility again, if you've not already done so. From that point, you should simply be able to run the extra monitors off the second card by attaching them all at once. Remember to use 'extend my desktop to this display' etc. as appropriate within windows.
     
  3. kdn

    kdn Member

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    It turned out to be the cable causing the issue, when just the 6670 was installed, with the dvi cable connected I would get a post error, when I reverted back to the original dvi cable it would work fine. when both cards where installed, and the 6670 had the bad dvi cable connected it just wouldnt initialize the card and I guess because there was a second card available it didnt give me a post error it just left the 6670 disabled - hence why windows wouldnt see it. changing back to the other dvi cable I could get both displays working one off each card perfectly.. so weird.

    Only difference between cables is the working one is a single link 1.8 meter, and the bad one is a 3 meter dual link. so I am going to try and buy a 3 meter single link and pray that works.
     
  4. sammorris

    sammorris Senior member

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    Strange the things that can happen, I had a PC keep powering off by itself and not POSTing some of the time, with the PSU making a horrendous squealing noise every time the hard disk was accessed (which disappeared with a different PSU, but not the other problems), turned out to be a bad S-ATA cable shorting out the disk controller on the motherboard. You'd be amazed what can go wrong with a faulty cable.
     
  5. staloned

    staloned Member

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    To respond to the question you have do you have any items in the PCI-e 1 SLOT ? As i have found that the Giga-Byte motherboard that i had had the same kind of setup and i couldnt use the second slot if there was something in the PCi-e 1 slot as thats the way they designed the board i had which is kinda stupid if you ask me ? I had 2 graphic cards in my 2 pci-e slots in cross-fire then bought a expensive sound card for the pci-e 1 slot . When finnally after several attemps to contact Giga-Byte they finnally told me to remove a video card to use the sound card as they desinged a lot of boards where the pci-e 1 slots took the pci-e video 4 bit slot away. Its either 2 pci-e video cards or one video and one of the single slot to use. You would think that all the slots on a motherboard would be useable but they screwed us all when they designed them. As now I have built a system with the motherboard where all 4 Pci-e slots are usable with the single slots as well and all is 16 bit not downgradded when using more cards. You have to research the boards carefully as after that Experience with Giga-Byte i wont ever by there motherboards agan. It took me over a month for them to respond when i had that problem and if you look at there boards they still have the same kind of issues when making them.
     

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