Samsung memory usually overclocks better, but it does vary unit-by-unit.
Additionally, what software are you using to change your clock settings?
Using MSI Afterburner to change settings. Also tried just the nvidia-settings under Linux as well.
1060 - Micron
1060 - Samsung
1070 - Micron
1070 - Micron
1080 - Micron
1080 - Micron
I've tried to up the TDP to over 100% (power usage not an issue for me) and that didn't make a difference.
Stats (no overclocking):
GeForce GTX 1060 6GB 104.07 W 85 % 76 1620 MHz 3802 MHz
GeForce GTX 1060 6GB 113.01 W 85 % 77 1670 MHz 3802 MHz
GeForce GTX 1070 157.30 W 70 % 64 1657 MHz 3802 MHz
GeForce GTX 1070 162.28 W 70 % 70 1657 MHz 3802 MHz
GeForce GTX 1080 161.54 W 70 % 59 1708 MHz 4513 MHz
GeForce GTX 1080 171.54 W 70 % 67 1708 MHz 4513 MHz