I do not think your RAM is limiting you - in other words...
Integrated Memory Controller = IMC or "Uncore" [as seen in memory tab of CPU-Z]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This is your culprit!
The IMC's vary in ability and "quality". Specifically - in regards to latency. Latency is comprised of 2x parts.. your NB/Uncore speed and relative timings, as well as your RAM speed and relative timings. Raising Uncore speed.. raises bandwidth/throughput, while lowering timings can do both increase bandwidth and lower latency. That said... every IMC has different limits.
You are starting to push your IMC latency hard with RAM speeds +2000mhz, as this requires NB/Uncore to be at a high speed as well. Uncore should always be 2x that of set RAM speed.. so if you are looking for 2200mhz RAM.. your NB/Uncore needs to be set to 4.4ghz in BIOS [by adjusting Uncore multi].
To get the IMC to this speed.. you will need to focus on QPI voltage as well as IOH voltage. [1.42-1.46v QPI should be safe for watercooling.. though you may not need that much..again every IMC is different, you may get away with 1.36.. or you may find you need 1.5 as well] for IOH voltage.. I would set 1.22-1.26v ..lower once you have found stability.
**As well.. when you are pushing for more RAM speeds.. its a good idea to try to leave timings on Auto if you are having difficulties getting to POST.. see what the CPU likes on Auto.. make adjustments based on what you see is different from your previous settings.
Hope that helps some..