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Efficiency: Enhanced efficiency, which increases your FPS Capacity: 32GB Kit Configuration: 2 x 16GB Speed: PC4-25600 (3200MHz) Memory Type: DDR4 Error Correction (E.C.C.): Non-ECC Voltage: 1.35 V
Efficiency: Great for games that use a lot of CPU, easily accessible Capacity: 32GB Kit Configuration: 2 x 16GB Speed: PC4-21300 (2666MHz) Memory Type: DDR4 Error Correction (E.C.C.): Non-ECC Voltage: 1.2 V
The motherboard can handle both 2666 and 3200MHz, but not concurrently.
To use the dual-channel, they have to be matched in a pair, which they are not. Most likely, they are being throttled for stability by the motherboard.
1×8 G.B. of RAM at 3200MHz will never outperform 2×8 G.B. of RAM at 2666MHz.