I recently purchased a refurbished Inspiron G3 15-3579 configured with a 1TB SATA HDD and a 16GB Intel Optane Memory PCIe SSD. I immediately referred to my service manual etc in order to upgrade the sata HDD with a 500GB Samsung EVO SSD. According to Dell and Intel documentation it is essential to disable the Intel Optane Memory prior to swapping either of the HDD's. Both Dell and Intel provide various sources of information explaining how to do this (including videos) but I discovered my laptop had a configuration problem and it seems that many others have variants of this same issue. The Intel Optane Memory wasn't operating at all.
I discovered that my system appeared to be using the Intel RST optane memory technology as I saw the PCIe SSD (the optane memory SSD) listed in "Device Manager" as working normally and it was listed in the Intel RST interface as a SSD running on the NVMe controller. Nowhere in the appropriate places did I see any reference to the term "Intel Optane Memory" and the Intel rapid storage technology interface was missing the "Intel Optane Memory" tab and just listed the Optane SSD running on the NVMe controller as a separate SSD naming the volume by the model number (INTEL MEMPEK1J016GAD).
So first I updated windows and all my drivers, but that didn't help. So I reinstalled windows via a clone I made of the original HDD and did all the above again, but still no Intel optane memory options appeared. I tried all the trouble shooters and nothing gave me the Intel Optane Memory options mentioned in the various manuals. Frustrated I decided to ignore this optane thing and swapped out the primary sata HDD to my Samsung SATA SSD and preceded to use the laptop for gaming without incident.
Now after hours spent researching the Intel RST optane memory technology, I found the reason for this problem is that at some point (for me it occurred before I received the laptop) a BIOS update sets the storage mode to AHCI for SATA which at first glance seems like the logical option of the three listed in system bios but renders your Optane memory technology completely absent. In the system BIOS the SATA mode selected has to be RAID or RAID On as this is the only bios option that will enable your computer to properly configure the Intel Optane memory array and show the "Intel Optane Memory"tab on the Intel RST. For my case, I had to uninstall the Intel RST driver and software before changing my BIOS settings to the correct option. Then I booted into Windows, reinstalled the necessary driver and software and now my computer is configured correctly and even faster.