Yes, but it will run at Gen3 speed -- the system is too old to support Gen 4 speeds.

Thank you @ejn63​ for your prompt response.  Yes, this what I thought would happen, but I wanted be sure that it would work.  I decided to consider this SSD since all other I was able to find were slower than PC611 NVMe SK hynix 512GB.  Thank you again.

PCIe 4.0 SSD stuffed into a PCIe 3.0 slot work fine and may be faster than older PCIe 3.0 SSD products

@HedgeFundManager​  Thank you, I appreciate your advice.   Today I am planning to buy the memory.

PCIe 5.0 is now widely available. PCIe 6.0 is seen in server SSD.

At its release, PCI-SIG commented that it did not see the PCIe 7.0 coming to the PC market for some time. Instead the interface is initially targeted at cloud computing, 800-gigabit Ethernet, and artificial intelligence applications.

On 5 August 2025, PCI-SIG announced the development of PCI Express 8.0. The specification is planned for release by year 2028. It will deliver double the speed of the previous version, 256.0 GT/s raw bit rate and up to 1 TB/s bi-directionally via x16 configuration.

In short PCI Express speeds will become fare faster and PCs will need faster main memory to keep up.