The side of your case that has the motherboard's backplate (where you plug everything in) is the bottom. On the vast majority of towers, the plate is on the right side, meaning left is up.
EDIT: right/left when looking at the front of the case.
The side of your case that has the motherboard's backplate (where you plug everything in) is the bottom. On the vast majority of towers, the plate is on the right side, meaning left is up.
EDIT: right/left when looking at the front of the case.