@gch233 , welcome back to the Community.
Unfortunately, the Product Specifications for the computer are not available. So, I am answering without the complete knowledge of the components in your computer. However, adding more memory should not interfere with the Optane in your computer. It is separate from the memory. I suggest that you use CPU-Z to find the manufacturer and timings for the current memory: https://download.cnet.com/CPU-Z/3000-2086_4-10050423.html
This information is in the Tab titled "SPD". It is best if the memory is installed in matching pairs to get the best performance from it. If you can't match it exactly, you should replace the existing memory, as well.
Please click the Thumbs up + button if I have helped you and click Accept as Solution if your problem is solved.


I am not an HP Employee!!
Intelligence is God given. Wisdom is the sum of our mistakes!!