The machine came fitted with a 128GB Kingston SSD which I've kind of outgrown. I tried replacing it with a 480GB WD Green, but it developed a really BAD freezing problem and although I've found plenty of search hits for SSD freezing there doesn't appear to be a clear solution out there. I've raised a support ticket with WD.
I'm guessing that either I have an odd compatibility issue that will go away if I buy a different make of drive or I need to update something.
Alternatively I'm wondering about fitting a regular hard drive as secondary storage but I'd rather have one volume.
Also since I'm never going to upgrade the graphics could fit a NVMe adaptor in the x16 slot?
[Edited the thread to add issue detail]