@TristianX
- There is no Z690 motherboard with guaranteed 4-stick support above 5600. Most don't even have that. Gigabyte Z690 Master has max 4800 in 4 slots on the QVL, so hard to say if they tested more.
- If you have problems with LAN like randomly disappearing then it can be faulty NIC -> RMA.
- If you have problems with M.2 sockets speed then check if you are not using other devices on the shared PCIe lanes. If you aren't then -> RMA. If you expect the fastest NVMe SSD to run at 7400MB/s then it's a problem of all Z690 motherboards as they can't make more than 7000-7100MB/s. It works at 7400MB/s+ only on AMD right now.
- There is no Corsair 6200 kit on the QVL, so support will tell you it's not guaranteed it will work. In this way they are "protecting" themselves from RMA. What is even more annoying is that most kits on the QVL were never released in retail and almost all 6200+ are only pre-release test versions. MSI support told me that if I prove them that I have 6600+ kit and it doesn't work on Z690 Unify-X at 6600-6800 then they will replace the motherboard. There are no 6600+ kits in stores at all, so how can I prove it? On the other hand, support can't prove that the motherboard works without issues as they don't have 6600+ kits too. This is a ridiculous situation.
Every motherboard that I can recommend and for sure supports 6200-6800 memory kits is 2-slot. I know that almost all ASRock motherboards have problems with 6200+, most Gigabyte, and most ASUS. MSI surprisingly can't make 6800+ on their Unify-X but even cheaper motherboards run at 6400.
Gigabyte Tachyon supposed to be tested for 7000, like every motherboard is tested for 7000 before it goes to stores (not sure if it's true but I saw that info somewhere posted by someone who works with Gigabyte). My Tachyon was working at 7000 for the first week, later had problems with booting.
It's like I can recommend only "lesser evil" as every motherboard will lack the features or won't support 4 memory sticks or won't run at higher RAM clock. Gigabyte Master is one of the best equipped Z690 motherboards as there is nothing at a similar price with 10GbE LAN or 5x M.2 sockets on the PCB. I also find audio very good. It "only" has that RAM support problem.
I will only add that my Z690 Master runs in my gaming PC with the 6200 Dominator kit at 6000, just because after retraining (simply after I turn off and turn on the PC) it sometimes has stability problems. With V-Color 6200 kit was almost the same. It was working stable or couldn't boot at all.
Gigabyte didn't forget about us. The same as every single brand, they are probably working on Z790 and AM5 motherboards already. The same ASUS, MSI and others have no new BIOS releases since ~April. There are only some beta versions for OC of the "special" OC motherboards like Apex, Unify-X, Tachyon etc.
In short, I would RMA your motherboard and later sell it and replace with something else, but I would read some reviews or user comments to be sure that the features you want/need are working.