  Fix a Calabi-Yau 3-fold $X$ satisfying the Bogomolov-Gieseker conjecture of
Bayer-Macr\`i-Toda, such as the quintic 3-fold.
  We express Joyce's generalised DT invariants counting Gieseker semistable
sheaves of any rank $r$ on $X$ in terms of those counting sheaves of rank 1. By
the MNOP conjecture they are therefore determined by the Gromov-Witten
invariants of $X$.
