Gotcha - well, the best CPU that motherboard can take it the
AMD FX-8320E and these can be found on
eBay for around $100 (used). However, you won't see much a difference compared to your current FX-6300, so it's not really worth it. You could always add in some extra RAM, increasing it to 16 GB in total, but again, the expenditure isn't worth it as no future upgrade will work with DDR3.
The best upgrade you could do is replacing the graphics card with something better - however, current prices are utterly ridiculous, even second ones, so you may well have to put with the GT 1030 for a while longer. Even when (if!) prices do return to sane levels, the main thing to note is your current graphics card takes all its power from the slot it sits in.
More modern cards need more than this and so use a PCI Express cable from the power supply unit. If yours doesn't have one, then you'll need to either replace the supply unit or use a molex-to-PCIe adapter.
Edit: One possible graphics card to consider is the GeForce GTX 1050 Ti - it doesn't need an extra power cable, and will be a much better card (still low end by today's standards) than your 1030. However, new models are
massively over-priced (over $300 on Newegg, for something that launched at $140) and even second hand ones are stupidly priced.