You can wait for the 4th gen CPU's if you want.
And yes, a b550 will work out of the box with 4th gen.
However, the motherboard you currently have selected I don't know the status of, and whether or not it ships with support for 3rd gen out of the box.
I've made a build for that budget using current options right now for you though, and you can just modify the mobo and CPU for 4th gen when it comes out if that's what you're going to buy instead.
The total build will work as is, but as stated, if you want to go with 4th gen, then the mobo and CPU in this build are just place holders at this point.
And since this build comes in at about $300 AUD under budget, you definitely have room to spare for newer components and if there's still room left to spare, it's possible to upgrade the GPU to NVIDIA perhaps.
Only time will tell if you are going to wait.
But as it is, this build I've put together improves upon your build in many ways.
I'll explain why I've chosen certain components now:
Motherboard:
I chose this motherboard because it's high quality, and supports 3rd gen out of the BOX without needing to update the BIOS before hand.
RAM:
Should be self explanatory, it's faster RAM with acceptable timings which is better for Ryzen.
SSD:
Do not waste money on an NVME that is so small in size, especially since it looks like it's going to be only used for main OS and apps like web browsers.
A standard SSD is more than fast enough, and I gave you more storage from it.
HDD: You said "seafarers" and I'm assuming that's a typo and you meant to say "Seagate". Regardless, I am making note of this HDD because it's affordable, and has not only 2TB at 7200RPM, but it also has a massive 256MB cache.
Power Supply:
The power supply you chose I believe is white rated 80+.
The PSU I chose is Bronze and higher quality.
PC Case:
I chose this case because it's more affordable, and while not the fanciest looking, has plenty of space inside for building, and a mesh front for great airflow. Fractal Design has never let me down with their cases for the most part. I also added 2x140mm fans for mounting to the top, and an additional 120mm fan for the rear of the case.
The case comes with 2x120mm fans already installed.
I then added fan splitters to the list so that you can connect all the fans to the motherboard.
GPU:
Lastly comes the GPU. It's a big upgrade from the 5600 XT you chose and will perform better in games at higher resolutions and such so yeah.
Anywho, here's the build.
PCPartPicker Part List
CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core Processor ($299.00 @ JW Computers)
Motherboard: MSI B450 TOMAHAWK MAX ATX AM4 Motherboard ($198.00 @ Skycomp Technology)
Memory: Crucial Ballistix 16 GB (2 x 8 GB) DDR4-3600 CL16 Memory ($160.60 @ Newegg Australia)
Storage: Kingston A400 480 GB 2.5" Solid State Drive ($94.00 @ Centre Com)
Storage: Seagate Barracuda Compute 2 TB 3.5" 7200RPM Internal Hard Drive ($98.00 @ Shopping Express)
Video Card: ASRock Radeon RX 5700 XT 8 GB CHALLENGER D OC Video Card ($614.20 @ Amazon Australia)
Case: Fractal Design Focus G ATX Mid Tower Case ($97.90 @ Newegg Australia)
Power Supply: Corsair CX (2017) 650 W 80+ Bronze Certified ATX Power Supply ($109.00 @ Austin Computers)
Case Fan: ARCTIC Arctic F14 PWM 77.3 CFM 140 mm Fan ($10.00 @ Skycomp Technology)
Case Fan: ARCTIC Arctic F14 PWM 77.3 CFM 140 mm Fan ($10.00 @ Skycomp Technology)
Case Fan: Deepcool XFAN 120 44.71 CFM 120 mm Fan ($9.00 @ Mwave Australia)
Custom: Fan Splitters ($17.00)
Total: $1716.70
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2020-06-04 08:53 AEST+1000
Facebook
Twitter
Instagram