I'm willing to build a pc with a Ryzen 3 1200 (A320 Motherboard, so no OC) and RX 570. Will I encounter severe bottleneck, or will the CPU handle the GPU just fine?
I would also agree with going with the 1600, if you can. With games starting to take advantage of more cores/threads, you will get more life, out of the 1600. If you live near a microcenter, you can get them for $79.99 and still get $30 off the motherboard. Pure quadcore gaming's days are numbered, in my opinion.