Best place, which is where I attach to.
1) Use a power strip - plugged in to outlet, switch in off position.
2) remove alligator clip.
3) Plug he bannana blug into the ROUND AC outlet hole.
Alternative.
With PSU installed and plugged in and PSU rocker switch in the OFF position, attach the alligator clip to a UNPAINED bare metal on the case.
If NO bare metal, run a screw into any screw hole on case and attach alligator clip to screw.