Upgrade graphics card alone

[aougli]

I'm trying to upgrade from 2014 to 2019 (or maybe 2017 or 18).

My current components are listed in my signature.

I haven't been playing much apart from Battlefield 4 and that ran fine. I'm now bought Origin Access Basic Vault and want to try Anthem, Titanfall 2, an Arkham game and others. Ideally Red Dead Redemption 2. I haven't used VR and most likely won't.

I was thinking about getting a new Radeon RX 5700 8GB GDDR6 graphics card for around £300. Is there any point in considering a Vega model as it's almost the same price as the 5700?

At some point in the next year I'll also replace the CPU, RAM and motherboard but I'm like to hold off for budgetary reasons.

Is upgrading the graphics card alone going to provide a significant improvement?

The motherboard is PCIe3.

I may be able to also stretch to a second hand i7-4790 3.6GHz (has to fit the LGA1150 socket) and an extra 8gb of RAM for around £100.

I'd appreciate any suggestions regarding the technology or cost. Thanks

 

[4K8KW10]

Your Enermax Infinity 720W has two 28 ampere 12V rails and one 30 ampere 12V rail https://www.jonnyguru.com/blog/2007/04/21/enermax-infiniti-720w-power-supply/
The new power supplies are designed with 1 12V rail that supports higher current, and modern graphics cards tend to exploit this feature.

The RX 5700 would give you around 95% performance increase, if it agrees to work with the PSU.

No point in looking at the Vega cards.
i7 is the preferred CPU for your build.