As of today (12/6/18), the 16GB 0X1NJ and 32GB PPD1R are the only cache SSD listed on the XPS 8930 parts page.

Thanks Chris, can you give me link to that page from which I can purchase it?

You will have to call Dell Spare Parts 1-800-357-3355 to see if they 32GB is available for sale. Just give them the 5 digit part number.

Some light reading, just in case you haven't seen it yet ..

https://www.intel.com/content/www/us/en/support/articles/000024018/memory-and-storage/intel-optane-memory.html