I've got almost the same as above:
Asus Prime x370 Pro BIOS 4011
R7 2700X @ 4.1ghz
Thermaltake Riing 360rgb AIO
4 x 8gb Trident Z @ 3000mhz
Samsung 960 Evo 500gb
R9 390X 8gb
I can get an ~4.25 max stable OC at 1.425, but I don't feel comfortable with that level of voltage, so it's been backed down to 4.1ghz at 1.4. Temps stay under 60c at load with prime95, but my office is also in the lowest floor in our townhouse, and it's always a bit cooler. Idle temps for me can drop down to 27-28c, but again, that has to do with my location in the house. I think if I was in the living room, I'd be right around 3-4c higher on average, but still very good. I run my fans at about 85%, (~1300rpm), so if I had max power, I'd probably get a bit lower, maybe 1c or so.
Getting a 4.3ghz OC will take some luck with the silicon, but will also require a very serious cooling solution. You'll most likely be pushing 1.4375 or more voltage. Yikes.