While the PCIe slots are gen 3, your M.2 slot 2 can only support Gen 2x4 speed. The SK Hynix P31 is a better choice over the DRAM-less SN550 and it has very good performance specs. You may want to look into using PCIe adapter to gain better speed.  But anything is still way faster than your current spinning HDD.
Hello. Transitioning my one main drive from mechanical HDD to SSD. Do not consider having two drives in the PC. Would you please be so kind as to assist me?  My PC is: Dell Inspiron 5675 - Octal Core AMD Ryzen 7 1700, Motherboard Chipset AMD X370, AMD Taishan, AMD K17 IMC. DMI Motherboard Product 07PR60. I would like to know which type of PCIe M.2 2280 SSD are supported. I am considering (SAMSUNG 980 SSD 1TB PCle 3.0x4, NVMe M.2 2280, Internal Solid State Drive.  [URL] I see PCle M.2 2280 on my Motherboard I am just not sure if it would support Gen3X4 or Gen4X4 SSD's. I run the Crucial scan and it claims to support all modern generations, but I would prefer to stick with the 3rd just to be on the safe side but I am not sure if Gen3X4 would work on the PC. I would prefer Samsung since the TBW's on them is 6 times higher than Crucial SSD's. But that is not the issue here.  I would like to know if I can simply purchase any 1 TB PCle 3.0x4, NVMe M.2 2280, Internal Solid State Drive. I do not see any lower generations on sale, nor I know if they exist.  I also have a SSD SATA option on the motherboard, but I would prefer to use the NVMe M.2 2280. Also, there is an issue with some of these SSD's that use some of the RAM (I have 32gb) for better performance, but there is a warning that if power goes out, system files get corrupted.  I do not mind if the system will run a little slower, just want to have one - 1 TB PCle NVMe M.2 2280, Internal Solid State Drive and remove the 1 TB 7200 mechanical drive from the PC. Any advice with compatibility would be  greatly appreciated.  Thank you very much.  
Inspiron 5675, SSD NVMe M.2 2280 compatibility?