Multiple G-Drives on my desk

Is it better to have multiple G-Drives laying horizontally as in the photos and stacked, one on the other or better to stand them up on their short side for better heat dispersal? I.E.: like = or like ||

generally horizontal is best, vertical can work but if it falls over to one side because it is standing on a narrow side then it could be bad for the drive.

I’m worried about heat build up if they’r stacked. I could put space between the stacked drives or I could mount them to u-shaped saddles that would keep them from tipping over if standing vertically. Other drives come with saddles like I mention but I could fabricated something.