Okay great, then you can get 2x4GB instead of 1x8GB. The 2 sticks will run in dual-channel and give better performance. I know they are slightly more expensive, but it's worth it.
Pick whichever pair you like as far as price and all
https://pcpartpicker.com/products/memory/#s=403000,403200&Z=8192002&sort=price&page=1
I know on Intel Z-series boards a 3000 CAS 15 will run overclocked at 3200+ CAS 16. I have 2 sets of ram both run OC'd at 3200 CAS 16 1.32V on Z270, and their stock speed is (Corsair) 2400 CAS 14 1.20V and (G.Skill) 2800 CAS 15 1.25V.
So like I was saying, lower cas and lower voltage are better by themselves, but especially if you want to overclock because you can increase both to allow faster speeds.
*I would probably get the G.Skill Ripjaws V 3200MHz. It costs more but it's already at 3200Mhz so just enable XMP in BIOS and you're all set.
**Wait, wait, wait,.. I forgot AM4 is picky with memory. Let's research which is most compatible before you buy.