New here, but went through the same foolishness on my Strix x470. Upgraded from my old32GB Crucial 2400Mhz setup that I carried over from my previous Intel build to a 32GB 3200Mhz setup, I went through 4 kits to get one right.
Corsair C16 LPX kit wouldn't even POST at 3200 (returned it and didn't even bother replacing, I wanted RGB RAM), the first RGB Pro C16 kit would post but fail memtest, 2nd kit was fine. I also ordered an RGB Pro CL14 kit which gave me fits even though its B-Die - memtest would fail a run, pass a run then fail a run. Replaced the Strix with a Crosshair VII on a lark figuring, 4 kits of RAM with issues, maybe it's something else, and voila, problem solved. The CL14 kit passed 2 runs (13 hours). I have a replacement SSD coming so I'll get a clean Windows build on it and should be good to go. I'd stick with a CL14 kit, would've saved me a fair bit of time, aside from the bad Strix.
Suppose I'll RMA the Strix...I'm not swapping a motherboard for the 4th time since summer haha