JOcean - thank you.  I was planning to: 1.  get an enclosure for the new SSD and link it to PC via USB 2.  Clone the current bootable SSD to the new one 3.  Swap the two SSDs over and reboot. Would that work? Yes. I did just this the other day.   I don't have your model desktop PC, but according to Crucial, the 3671 uses a NVMe SSD. [URL] here's a highly rated enclosure : [URL]  
I have a Dell Inspiron 3671 running W10 and I want to increase the capacity of my 'boot' SSD (my words - it is the PCIe SSD that fits onto the motherboard) from 256G to probably 512G.  Form factor 2230.  I think that I need to clone the existing one to a new one, but am facing a couple of questions: 1.  I can source a 512G from Dell ([URL]#compatibility_section) but am having difficulty in sourcing an enclousure to fit 2.  Can I use a form factor 2280 (for instance [URL] ) although I cannot find one that says it is compatible with my machine, bit there is a screw socket on the motherboard to fit (I think).  Enclosures for these seems to be more available. So: 1.  Any general comments on my plan 2.  Where can I source an enclosure for the form factor 2230 in UK 3.  Can I use the 2280 form factor Thank you in advance
Increase capacity of 'boot' SSD