It's called 'shove a used gpu in there'. $170 on a used gpu will probably get you a bigger bump to gpu perf than going from the igp of a 56/5700g to that of a 8500G. and the kinds of card you're looking at probably wouldn't be troubled running at pci-e 3.0x8... Sure the IGP of these APUs is probably much improved... but as i said above, the 8300/8500G only having 4 lanes of pci-e 4.0 for a gpu means you're probably in for a less than stellar time should the igp become insufficient and you're contemplating putting a dedicated card in there...
Fair, I was thinking more for smaller form factor e.g. HTPC use or for low power rigs, but yes, if adding a proper GPU is an option that’s going to get you far more performance.
I pretty much use one of these daily in my handheld (7840U) it is really very good there nothing I can't play on in and I have a 30w TDP limit, you have to of course make concessions with resolution scaling and quality levels etc, great for a HTPC or other small form factor depending on your expectations, the extra bump in TDP won't magically make it that much more powerful that the handheld for gaming, the power will predominantly get swallowed by the CPU.
