What are the best options for a PC Upgrade?

I would like to upgrade my PC, my current setup is not the best, and although I don't ask much from my computer it is certainly not the fastest, I think when I got my computer back in 2018 I could have got a better setup, which is why I'm asking for help here. So back in August 2018 I custom built my PC on the PC Specialist website, and although its not terrible I could have ended up with something better, so for example when it comes to choosing what processor I need I haven't got a clue. I've had a look on the website and gone though the process to custom build a PC, but I don't really know what I need. I think this is why I haven't got the best computer from when I did this last time.
What I would like to do is keep as much as possible and only upgrade what I need to, so the outer case, DVD drive, memory card reader, power supply I could keep, and just replace the motherboard and whatever else I need to. Another question this raised is would the current power supply be sufficient or would it need to be replaced, what graphics card is most suitable etc.
My current PC needs are not that high, its mostly internet browsing, converting video files to DVD, and a few games but nothing major, I think the newest game I own in SimCity 2013, so now 11 years old, which runs through the EA programme. I currently have a 500GB HDD but probably would double that in an upgrade just to ensure I would have enough space for the future, although currently only 238GB have been used so far. The thing I want most from an upgrade is performance, as at the moment simple things take too long, and have tried everything to improve performance, but the computer has never been as quick as I'd like it to be.
My current PC Spec is correct as listed in the "My Computer" tab below. Any advice would be much appreciated.

Are you in the U.S. of Biden?

What's your budget?

The top of the line CPU for your MOBO is the I9 9900 (minus the K SKUs. (Stock Keeping Unit) Don't need those. They're for overclocking).

On eBay that CPU will run you around $270-$300. "Core I9-9900" in All Categories - PicClick

Or you could go i7 9700 which would run you around $150 or less if you look for the deals and use what I use called Item Alert. Item Alert: Fast & Free eBay Alerts and Notifications! [home]

You do want to make sure your BIOS is updated BEFORE you install a new CPU though. PRIME H310M-A - Support

I would also upgrade the memory from 8 GB to 16 GB.

You could get yourself a fast M.2 NVMe drive. According to your manual, once you install an NVMe drive SATA 2 is disabled. Also, the NVMe drive will only operate up to PCIe 2 speed. In lieu of an NVMe drive just get an SSD drive. At least 1 TB. I use my primary 2 TB NVMe drive for the OS and whatnot and then a second 2 TB platter hard drive for downloads and other stuff. That way it helps on wear and tear on the NVMe drive and capacity. Flash based storage has a finite write capability. Though, today it's pretty massive. My drive will handle 440 TBW written to it. Others are higher, but I think that may be subjective. Samsung may have the highest drive write ability/TBW. How Long Does an SSDs Last? | Calculate Your SSD’s Lifespan


A PSU (Power Supply Unit) should be replaced every 5 years, but that too may be subjective if it's a good reputable unit.

I'm in the UK.
And I don't really have a budget as such, I'm happy to pay for whatever gets me a good system. I think my current setup only cost £500, so I don't want to get anything that's too cheap, so I wondered what the minimum would be that I would need to pay to get a decent system.

Bastet said:

If you have a HDD then upgrading to a SSD will speed up the PC.

Yes I have just a standard HDD, so I would be looking to get a SSD alongside the HDD.

Yeah that's what I was thinking, to replace the current HDD with a larger capacity one, and have an SSD alongside it which would have Windows installed on it.

Use the platter HDD for downloads and whatnot.

I think I have enough information to be looking into things further, I have a better idea of upgrade options. So for now I'll mark the thread as solved, but will come back to it if I need further assistance.

If you have many $ then you will can have what you want.