What are your needs? Why do you need 32GB of RAM? There are a few things that do not make sense in this build. Are you looking to use it for gaming or as a workstation? Do you really want 4k?
First thing I would do is get a B350 motherboard instead of an A320. Even better if you get an X370. Second thing would be to get a 16gb kit of ram (2x8gb) instead of two individual sticks of 16gb ram. The higher the rated overclockable frequency and the lower the timing the better it will be for Ryzen. Third thing ties the monitor to the graphics card. Right now you'd be lucky to find a single graphics card for a decent price. I see that you have a 4k monitor listed, you would need a 1080Ti to efficiently run games in 4k @ 60fps. For a 1080, I would recommend 1440p. Look for a monitor with a high refresh rate with low latency. I purchased an AOC Agon to go with my 1080 and it only cost me $300. If you're adamant in purchasing a 4k monitor instead then I would go with a 1080Ti. This is if you want to build one right now.
My ultimate recommendation is to wait. Save up another 300 to 500 dollars and wait for 3 major things to happen.
1. The GPU market levels out again after crypto mining cools off.
2. AMD to release Pinnacle Ridge Ryzen CPUs.
3. Nvidia to release their next gen GPUs.
At least 2/3 of those will happen this year. Save your money and wait a little longer.
If you decide to build now, these are the changes I would recommend:
https://pcpartpicker.com/list/RQXRsZ
Keep in mind that GPU prices are high so the ultimate cost will be high and that you will need to purchase more fans for that case to keep things cool in there.
