I have the following issues with the x470 Taichi:

I have 2x 8GB sticks of G.Skill Ripjaws 3200MHz 14CL, so 16GB in total. Earlier this year I managed to run that memory at 3466MHz with tight subtimings with my x470 Taichi and a 2700x.

Today I changed some fans in my case. I unplugged all power cables but in general I haven't touched the sticks or the bios at all. All of a sudden, my system doesn't boot into those settings anymore. Fair enough I thought, so I set it back to standard XMP-settings, but it wouldn't boot as well. Then I tried 2400MHz with auto on all the subtimings and 1.45V on the the sticks. It wouldn't even boot that. So it basically can only boot in the default safe 2133MHz settings. I tried updating the bios to the newest stable Bios, to the beta bios, as well as going back to the last stable bios, nothing changes the outcome. 

I then checked the sticks and they are both fine. When I put in only one of them, so single channel, it boots with the standard XMP-settings just fine. However, as soon as I put them into dual-channel, it is impossible to set anything else than the standard safe setting, not even lower clocks.

Another issue I have is with the NIC. When I have both the WLAN Module and the onboard LAN Module active, the board either can not connect to the internet at all or after several minutes of waiting. As soon as I deactivate the onboard LAN, it connects straight away with no issues at all.

I hope you can help me, because I can not make sense of this.