Need advise on my upgrading pc!

Hello everyone,
I am having a hard time to figure out a decent upgrade for my pc. I have a compaq pro 6300.
I was about to add a sabrent nvme M.2 SSD to Pcie x16. I have the pci x16 free so no problem with that. I am still undecided if i go with the SILICON POWER 1TB or the 2TB.
My cpu is a I5 3570. So here is the dilemma. My motherboard i dont think it support the nvme boot from pcie, from what i understood, and the latest update is in 2019 but does not mention any nvme capability. Here is the question… if i still go for it, it will not be bootable but will it work on linux anyway? If yes i suppose my plotting will anyway improove big time… my plot time is about 24 hours :sob::sob::scream:. I have for the moment 20GB of ram… 2X8 and 1 of 4. Ideally if i cam make work the nvme ssd i will add 16GB ram and put the other 4 on another pc. That will breng me at 32GB of ram. This will give me the chance to start to plot my hard drives.
I know the best would be get a new pc. I will probably do that in few months so i was thinking that eventually this pc would be the farming system and the new one the plotting one. All suggestions we be welcome:)
Thank you.