As far as processors go, the strongest upgrade available on your motherboard would be a I7-3770K.
They sell for $60 or so on ebay. Probably a decent cpu upgrade.
4 more threads and a single thread boost of perhaps 30%
But, what you really would notice is to upgrade Windows C drive to a ssd.
You can get a 1tb samsung 870 EVO for $85.
https://www.newegg.com/samsung-1tb-870-evo-series/p/N82E16820147793?Item=9SIBGHXJCS2872
500gb is half that, but you should want room for expansion.
You WILL notice how quick everything feels.
There are cheaper ssd devices out there, but not quite as reliable as Samsung.
Samsung has a ssd migration aid that will move your C drive to a ssd easily.
The nice thing is that a ssd is easily transportable to a new build in the future.
As noted above, your psu is questionable and should be upgraded if/when you upgraded the graphics card.
Do not be seduced by a low priced cheap psu.
A cheap PSU will be made of substandard components. It may not have all safety and overload protections.
The danger is if it fails under load, it can destroy anything it is connected to.
It will deliver advertised power only at room temperatures, not at higher temperatures found when installed in a case.
The wattage will be delivered on the 3 and 5v rails, not on the 12v rails where modern parts
like the CPU and Graphics cards need it. What power is delivered may fluctuate and cause instability;
issues that are hard to diagnose.
The fan will need to spin up higher to cool it, making it noisy.
A cheap PSU can become very expensive.
Do not buy one.
The simplest way to estimate quality is to look at the warranty.
Some with 5 years are ok, but look for 7 years or more and you very likely will get a good quality unit.