i'm looking to upgrade my pc parts. below is my speccy (don't pay attention the to temperatures, i'm like 99% certain speccy is off on temps)

please speak to me as if i'm 5. computers are NOT my thing

3950x is still a beast cpu you prolly don't need to upgrade that

your ram isn't running at the best speed... not sure what ram sticks you have but you prolly want ddr4 3600mhz speed. you can prolly change your ram speed in the bios I would look up videos on how to do that. like I said not sure what your max speed on your ram is but I bet its more that 1333mhz.

prolly get a faster hard drive your motherboard supports 2 pcie gen 4 m.2 nvme so i would get a one of those.

your graphics card is ok I guess for 1080p but I would look for a more recent Rtx card or Amd card with at least 8gb video memory.

100% agree with User Selected. Definitely enable higher ram speeds (doesn't cost you anything, just search how to improve Ram speed (add your motherboard's SKU to the search for specific info on your BIOS)

Depending on region, you might find a good deal on a 3000 series Nvidia card or 6000 series AMD card for GPU that would compliment the rest of your build nicely.

I'd recommend 3060ti or 6600xt (depending on price) where you'll notice a big difference at 1080p gaming but also have room to upgrade a monitor. 1440p at 144hz is amazing and super reasonable for price at the moment

What is the general use that you have for your PC? Are you only gaming? Are you doing any type of work on it, if yes, what kind of work?

Three components could use an upgrade. The build would definitely benefit the most with a GPU upgrade, then a RAM change, and if you're only gaming - a newer CPU from AMD - Ryzen 7 5700X3D.

Let me know how much and what kind of work you do on your PC and I'll make a suggestion as to what should be upgraded first

Vouch for 6600