Uhh, no offense, but the FX-series Bulldozer / Piledriver / Vishera CPUs, weren't even good in their prime. Don't waste your money upgrading that piece of.... history, to put it gently.
Save your money, if you want an upgrade, get this:
Ryzen R5 2600 CPU (6C/12T) $120 @ Newegg
B450 micro-ATX mobo, $65 (?) @ Newegg (doesn't matter what brand, much. MSI, ASRock, Asus, are good. Gigabyte, well, maybe.)
16GB kit of DDR4-3000 or 3200, $60 (seems like it's getting cheaper every day). You can get 32GB kits (2x16GB) for $120, name-brand like Crucial. If you wanted to "do it up". 64GB RGB kits of GSkill were ~$305 recently, but those sold out pretty quickly.
Then throw in your 750ti video card for the time being, and then get a GTX 1660 Super when they come out at the end of Oct., or maybe an AMD RX 5500 XT, sometime by the end of the year. (Or something more powerful, if you're a big-time gamer. Those are just the minimum I would recommend for a gaming rig these days.)
Edit: The Ryzen 2600 is probably 2x-3x faster than your FX-6300, to put it mildly. Especially for gaming purposes.
Edit: Ok, I'm going to make an exception. If you can find one used, an 8-core FX CPU, that's 95W, and under, say, $40-50, then sure, go for it. But don't spend any more than that, IMHO, because it's throwing good money after a "bad" (obsolete) platform.
And, honestly, I'm not sure that I'm aware of any modern PC games, that will refuse to play properly on an FX-6300, that will play properly, on an 8-core FX CPU. I'm not sure what you're gaining from this, realistically, other than a certain sort of peace-of-mind, that you "maxed out" your current platform.
My evaluation of this situation might be different, if you have an established Windows installation with a lot of programs or otherwise having a hassle doing a re-install on a new (updated B450) mobo. That would change things, and in that case, I would say, go for it, get whatever maxed-out CPU that you can for your mobo if you like. Just keep the price of the (new, replacement Ryzen system) in mind, when comparing options.