I assume this is a G2020? Unaware of any Pentium G2090. Assuming that is the case, you're not likely to see any benefit beyond a GTX 750/750ti or an R7 260X. As Slumy notes, if budget isn't an issue, a full platform upgrade would be ideal.
What are you looking to do with the PC? That's a pretty low-end processor, so if budget isn't an issue, it may be worth looking into upgrading the entire system.
I assume this is a G2020? Unaware of any Pentium G2090. Assuming that is the case, you're not likely to see any benefit beyond a GTX 750/750ti or an R7 260X. As Slumy notes, if budget isn't an issue, a full platform upgrade would be ideal.