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Windows can't detect second graphics card

Last response: in Graphics & Displays
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Anonymous
a b U Graphics card
May 26, 2010 8:00:32 AM

Hey there. :hello: 

hope someone here can help me..
im not new at all to computer and building them my self..
but this time i have run into a problem.
the problem is that my windows/motherboard can't detect my second graphics card?

what i do is..
i boot into windows and uninstall CCC and drivers..
my first graphics card is install from the beginning and is the one primary i use.and it sits in pci-e socket 1
shutdown. disconnect power source
install graphic card number 2 i pci-e socket 3 install the 2 bridges
plug in power and boot
now i get a black screen but can hear that it boot in to windows..
i power it off
and then move the screen cable(dvi) to the second graphics card
and then boot agian..
now i get a picture and it all..
but there is the problem..
windows cant not see the graphics card nubmer 1.. i device manager or even if i install ati ccc it can't see it there ether ?

Onboard graphics card is disable (HD3300) in bios..


PSU: shg titan 2 700w
Moatherboard: ASUS M3A78-T (bios 1801)
GFX 2: ASUS HD4850 TOP 512mb
Ram: kingston 2x2gb pc2-6400
CPU: Phenom II x3 720 be
dvd-drive
OS: windows 7 ultimate 32bit
a c 125 U Graphics card
May 26, 2010 8:56:31 AM

You don't have to do all that to get crossfire working.

1) Install one card into the first PCI-E lane
2) Boot into windows, and install the latest ATi drivers.
3) Shut down and install the second card into the second PCI-E lane
4) Connect atleast 1 crossfire bridge
5) Boot into Windows and Crossfire should be detected and It should ask you if you want to enable Crossfire.

If it doesn't ask you then load CCC and go to the Graphics tab and then click on Crossfire X and then enable.
a c 106 U Graphics card
May 26, 2010 5:18:20 PM

So what you're saying is, when the first card is installed in the blue PCI-E slot, it works fine, but when you install the second card in the white PCI-E slot, the first card no longer works but the second card works fine. Download GPU-Z to see what it tells you. It should tell you with both cards installed that you have two cards with 8x PCI-E lanes. Take out the second card and make sure GPU-Z tells you that you have 16x lanes when you only have one card in the blue slot. If it says 8x or anything else, then your board has a problem with the first 8x lanes.

Also try running the computer with one card in the 16x blue slot, and another in the 4x black slot. If it still has problems then I would guess one of the cards isn't getting enough power. If it works and detects both cards, then that means your board has a defect when trying to split the 16x lanes into two 8x lanes. In that case you have to RMA it.
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