The general consensus is that drive orientation does not matter. Makes sense to me, the parts are fixed, they're not heavy, gravity does not affect them. Howe

The general consensus is that drive orientation does not matter. Makes sense to me, the parts are fixed, they're not heavy, gravity does not affect them. However I've not seen anyone test this in real life. FWIW I've only ever had drives mounted horizontally, the normal way and upside down. All of them had about the same lifespan.