The Radeon and FirePro drivers are completely different, and as such Windows can't use both of them at once. Windows will either disable one of the two GPUs, or apply the "Standard VGA Adapter" to the second card. Unfortunately there is no way to get a Radeon 7990 and FirePro W7000 with fully-functional drivers to work simultaneously on the same system, it will have to be one or the other.
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