Yes, go to the EYEFINITY page on AMD's website and read up on it, all that information is readily available there.
After two legacy connections are used, then you'll be needing a native displayport monitor and/or an active adapter .. as per their Eyefinity setup guide. There are no active HDMI dongles/adapters, so you'll have to use an active VGA or DVI adapter.
As for the HDMI thing, it may override the default soundcard if it's an onboard realtek based soundchip, but you just go into the sounds options in Windows and reset the preferred sound device to default. Nope, I use a discrete PCI soundcard and no issues ever ..
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