To install TwinPlex on a AOpen i915GMm-HFS I think it's necessary to use Blende GeForce 6800 for the processor and Blende Gigabyte for the chipset.
Unfortunately AquaComputer doesn't propose TIFF-Datei for these two "Blenden".
your gonna have to take a chance on a twinplex fitting your
CPU. this mobo has a bad rep as AOpen used there own hole
placements on this board so none of the aftermarket HFS
CPU coolers will fit. maybe if it does not fit you could make
your own bracket.
imo tho id ditch it and get another board. one that uses
standard hole placements. sorry i cant get any other advise
as im not into micro-ATX boards.