GPU upgrade from R9 270x to RX 480?

Hey there, I have to show you this. https://www.youtube.com/watch?v=lQzLU4HWw2U
As we all know, the FX 8350, despite being a great multicore processor, lacks single core performance which is really needed for gaming. Thus, it is susceptible to suffer from the same problems as shown in the video. (It actually does suffer, I saw gaming benchmarks about it before, I just can't find it now) Although there are no benchmarks to prove that the RX series will have the same problems, it is very likely that they will. If for the same amount of money, you can find a GTX 1060, I think that would be a better option. Btw, yes your PSU will handle it well.

P.S. Contrary to some belief that AMD CPUs and AMD GPUs will work better than AMD CPUs, and Nvidia GPUs, that's incorrect.
Take a look at these benchmarks.
http://pclab.pl/art63116-48.html
http://pclab.pl/art63116-47.html
The Nvidia card works better on AMD CPUs, and weaker Intel CPUs in general

I have a 8370, and I used to have a R9 270x. Playing The Witcher 3, Verdun, TF2, X-Com2, PlanetSide2 ...
I decided to upgrade my graphic card and got me a Sapphire Nitro+ RX480 and let me tell you straight: I obviously saw a tremendous improvement. Witcher is way more fluid, I used to have some hicups while walking in towns, not anymore. It's fluid, with a configuration set to Extreme.
I've installed the card last night, haven't tested it fully, will do that this week-end. But I've launched all those games to see how they were looking, and they were looking good. I coundn't hear the card, so..
To be precise, I bought at first a Nitro+ 470 4GB but I sold it to get the Nitro+ 480 8GB, eventhough I was pretty satisfied with the 470. Cooling was great, performance were great too, but since my display is 1920x1200, I thought it would be better to get a 8GB version of the card. Or maybe it's because I'm a bit of a geek
Anyway, since we have the same config, I thought I would drop you this post

Your PSU should be fine. That's a 3-tier jump for your GPU (http://www.tomshardware.com/reviews/gpu-hierarchy,4388.html), & the current recommended GPU for "best performance @ 1080p/good performance @ 1440p (http://www.tomshardware.com/reviews/best-gpus,4380.html#p4). So far, the 4GB models are supposed to perform just like the 8GB models, although the Techspot benchmarkers have freely admitted they've had to rely on BIOS "tricks" from AMD (i.e. they used a special BIOS update to the 8GB cards to limit them to 4GB), as they hadn't had a chance to test actual 4GB models.

The GTX 1060 is another good choice as well. It tends to perform better (about 10-15% better on average)...but the lead either disappears or flips if you get a game with DX12 support (AMD's support for DX12 apparently working better than nVidia's). However, the main reason Tom's Hardware picked the 480 over the 1060 was price, as the MSRPs from nVidia & AMD had the 1060 priced 25% higher than the 8GB 480 & 50% higher than the 4GB 480. That being said, you really won't regret picking either of the cards, so whichever one you can get the best deal for should be your top choice.

As for CPU...I'm not going to get into yet another AMD vs. Intel debate, especially since you didn't ask us for a GPU upgrade (just a CPU upgrade). From personal experience, I've been very satisfied with my FX-8320 (identical to your chip, just clocked a little slower). I'm also gaming in the same resolutions you are (technically sub-1080p, as my monitor only goes to 1600x900 resolutions), & I used to have an R9 270X (replaced it at the beginning of the year with an R9 380, as I couldn't wait for Polaris). So the only thing I will say about CPU performance is...it depends on the game.. I can show you benchmarks where the FX-8350 suffers in comparison to an Ivy Bridge or Haswell i3, but I can show you benchmarks where the FX-8320 & 8350 not only easily beat a Skylake i3 but are within 10% of the performance of Haswell & Skylake i5s & i7s. I can even show you benchmarks where the performance of the chips is so close that they're literally within 1-2 FPS of each other. And in many cases, even when the Intel chips handily outperform their AMD competition, for the majority of gamers it won't even be a factor because with the right GPU the AMD systems are still capable of reaching the magic 60FPS number (i.e. matching frame rates to the monitor refresh rates). If your monitor can't display beyond 60 FPS, it doesn't matter if your system can hit 65FPS or 105FPS with all of the eye candy turned on, because you won't see it.