Upgrade the CPU(and extras) or the GPU

[Deleted]

As the title states I am looking to upgrade either the CPU, Motherboard and RAM or the GPU, problem is I'm not sure which one would have a better impact.

Currently my setup is "OK", it runs most things without a problem:
CPU: AMD-FX 9590 (OC to 5.0)
RAM: 4x4 1334Mhz Kingston Hyper-X
GPU: AMD Radeon R9 290X

Currently thanks to the meaty (and power hungry) CPU I can run WoW fine on level 4 settings. That may or may not seem low, but I'm honestly quite surprised it's still alive after the pain I've put it through - the story behind that is not having a sufficient Watercooler as it trickled water from the pump/reservoir to the CPU block, the temperature when I had that was 80/90C when running WoW, however now having a proper pump it sits at 40C with the overclocking.

Here is what I was looking to upgrade the parts to, either:

1. Change the CPU and components
AMD-FX 9590 -> Intel i7-8900K
Kingston 1334Mhz -> Team- T Force RGB 2666Mhz
(of course I'll need to buy a decent motherboard and a new waterblock too)

2. Change the GPU
Radeon R9 290X -> GeForce 1070ti

Any thoughts would be appreciated as I honestly don't know what to upgrade, I know people say "WoW is CPU intensive" but I also see people saying a good GPU affects performance quite a lot too.

[Illuman]

GPU affects performance once you get into higher resolutions and higher frame rates. So think, past 1080p, and over 60fps, this being said, WoW still likes fast core speed.

WoW really only takes advantage of a single core, so the rumored 8 core 8900k, will be absolute overkill. You will get similar gaming performance from the i3 8350k, i5 8600k, and i7 8700k. If you play other triple a titles, or do any other type of productivity work that requires more cores, you cannot go wrong with any of the mentioned. As for now, the i7 8900k has not been announced.

My recommendation, if you want to upgrade, with GPU Prices, and DDR4 prices being unreasonable currently, I'd do one of the following:

If all you do is game, check out the i3 8350k (this is basically a new version of the previous i5 7600k), but with only Z370 boards being available, you may as well move to a 6 core, and do either the i5 8600k, or the i7 8700k (if hyperthreading is important to you), grab 16 gb of DDR4-3200, and a GTX 1050ti, or a GTX 1060, and see how that handles your performance. If you find it lacking still, try to find a deal on a better GPU.

FWIW, I run a i7 8700k with a GTX 1080ti at 3440x1440 with 100hz refresh. I have little problem running most games at maximum settings and maintaining my monitors refresh rate. It is absolutely overkill for WoW, but with WoW not really maximizing modern/good hardware, I still see frame drops.

[Deleted]

As for now, the i7 8900k has not been announced.

Yeah that's my bad - I was supposed to put the i7-8700k.

When running some tests it's recommended to swap my GPU out for something more recent as it's bottlenecking which I'm more than happy to upgrade, but the problem is with the GPU's being so highly priced at the moment it would cost less to get a decent motherboard, CPU and new RAM.

Sadly I'm convincing myself that no matter what I'll replace, I'll have to replace the other to see any real performance gain.

[Illuman]

Like I said, try a lesser priced GPU, like a 1050, which is more than enough to do wow at decent settings at 1080p, WoW sees its largest gains from the CPU though, until you play at higher resolutions.