Hi!

Please un tighten the SB screw so the screw is leveled with the thumb nut.
Regarding the 5850/5870 backplate we already found this problem and informed all resellers about this problem that this backplate is compatible without modifications only for 5870 radeons. We have now, since 2 months already fixed versions that fits on both 5850/5870.
However if you cut or dremel off that standoff you not have problems any more.