Your memory kit is rated for 1.45v which you have the Dram voltage set to.
Intel recommends a maximum of 1.50v for the Dram voltage so you can safely try up to that.
For 4266MHz, you may get better results setting your ram manually rather than using X.M.P.
Try Tweak mode 2.
Tweak mode 1 helps with compatibility
Tweak mode 2 helps with overclocking
Whoa, yeah that is a nice gaming set up for sure you have there.
You're running 32GB 4266MHz cl 17, that is fast. With that, I wouldn't expect X.M.P. to work straight out of the box. The further you stray from 2133MHz and the more capacity you add, the more strain it puts on the cpu's memory controller, this is where I think your instability is. Some slight voltage adjustments and you should have it.
For just gaming, 32GB is more than enough, 16GB (2x8GB) is enough and is what I use (see my specs), 16GB will give you the best chance at hitting the highest speeds.
For a work computer it's pretty much the opposite, higher capacity with lower frequency to ensure stability.
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