most aftermarket cases are ATX, incompatible with 760 motherboard which is BTX.  If you want to move 760 SFF to bigger case, consider mini tower MT optiplex 780/760/755/745/740 cases which are all BTX.  Optiplex changed to ATX starting at 790. another serious issue is that different optiplex front panel pinouts can often be different. A 745 front panel cable does not fit 760 front panel.  The easiest switch is 760 MT case.  For other MT case you may need to transplant a 760 MT front panel circuit board into new case. Not an easy project. someone did extensive research on old optiplex FP.  [URL]
I have a Dell Optiplex 760 small form desktop, and I’ve been looking to upgrade it into a gaming PC. I have a new power supply that the compact case of my 760 just won’t allow me to install. So, I guess what I’m wondering is if I can take the motherboard and other components from the 760 and put them into a more accommodating case? Thanks in advance.
Swapping an Optiplex 760 into bigger case