I have an XFX HD 7770 video card with two DVI ports off the back. Only one of them is detected in Windows 7 64bit when I have two monitors hooked up (one to each port). I would assume if there are dual DVI ports you should be able to connect like I have it? Any suggestions? I already upgraded to the latest drivers. Note that both monitors work on the DVI 1 port but not on the DVI 2 port.
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It sounds like a faulty port. Probably best to RMA.