Hard drive e·lec·tric·i·ty and performance

It is common knowledge that SSD's are more energy efficent, but just how much, and does anyone really look at the numbers?

Test Rig:

-Dell Precision T30, Intel G4400 CPU, 8gb DDR4 RAM, Windows 10 installed onto Gen4 NVMe drive. MicroSemi 12gb SAS HBA card.

Test proceedure: all tests were done with SAS card installed, Windows 10 was booted up, and let idle for 3 minutes before taking inital reading.  Atto Disk Bench was run, and observed peak, and average wattage values from a Kill-A-Watt.  These values are somewhat subjective as we are relying on humans.  Not super scientific, but good enough.

A: Test rig with no drives:...................................27w idle.

B: Test rig with no drives, SAS card installed:.....34w idle.

C: Samsung Evo 840 1tb SATA SSD.................37w idle; 43 avg; 60w peak

D: Seagate Barracuda 250gb 7200rpm SATA....38w idle; 47 avg; 53w peak

E: Kioxia 1.9tb Enterprise SAS SSD.................38w idle, 45w avg, 62w peak

F: HGST 10tb 7200rpm SAS............................42w idle; 46w avg, 64w peak

Observations and conclusions:  I was suprised that just having the SAS card in the machine consumes roughly 7 watts alone.  Enterprise SSDs get HOT!  Doing two back to back runs of the benchmark the drive is almost to hot to hold. For the home lab I would suggest getting consumer SSD's to save heat and electricty if one doesn't need that last bit of endurance. So if one needs say 8tb of usable space, and speed isn't the primary issue would one be better off running two SATA/SAS drives in a mirror or four 2tb SSDs or three 4tb SSDs in a RAID5?  Well basic math seems to point that spinning drives would not only be cheaper to buy but to run.  Obviously speed and longer Mean Time Between Failure is longer.