On Sat, 26 Jan 2019 14:45:00 -0500, Yousuf Khan
wrote:

One choice of drives is a 5900 RPM 256MB cache. The other is a 7200 RPM
64MB cache.

A 5900 rpm drive will run significantly cooler than a 7200. I run both
speeds in the same brand/model of USB external box. The drives are all
4TB each. The 7200 drives run at 35-39 C while the 5900 runs at 25-30
C. Thus, the 5400 drive should have a longer effective life based on
cooler drives tend to run longer due to lower temperature stress on
(electronic) parts.