There are two compatibility issues to worry about when buying a bottom bracket (frame and crank). The 7series SC accepts a BB86.5. The gxp indicates that that BB will accept gxp compatible cranks (some SRAM, vision, etc), but not others (shimano being the main one incompatible)

To fit a gxp crank, get a gxp BB86. For, say, a shimano crank, get a BB86 Hollowtech