I also have an "original" CM690 case! Alas, the previous owner mangled all the top USB ports.
I know it can fit a reference 10.5-inch 980Ti.
The 980Ti Strix is reported at 12.0 inches in the
the techpowerup GPU Database. My experience is that their measurements are sometimes off by 1/16" (the thickness of the backplate), but no more.
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[/Korth]