I have been testing the Intel Optane drives. I usually use a fio command to test the ability of a drive to sustain forward traffic in a busy, large data content delivery website. Memory will act as cache for the site but the underlying I/O subsystem needs to feed that cache.
I compared two x16 large PCIe cards, the Intel P3500 NVMe drive and the Optane drive. What I found interesting is that the performance of the Optane per PCIe lane is much higher. This allow the Optane drive to reach similar levels of performance with two PCIe lanes as the P3500 with four.
In addition the CPU system time went down from 64% to 49% approximatelly.
If you have a busy web server with high system time and your fav motherboard or CPU runs out of PCIe lanes caching on an Optane or storing in Optane might be the solution.