My First Build - Please Help

[Nerevarine]

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PNP: Plug and Play automatically overclocks the memory up to the system maximum specs.

if you are running it at 1866 mhz, then your system maximum setting is not 1600 mhz..
There is absolutely no way, you will be able to use a memory at higher mhz on a board that does not support it

and Gigabyte Z97M-D3H does support 1866 mhz memory..
this is what I got from Gigabyte's website

Support for DDR3 3100(O.C.) / 3000(O.C.) / 2933(O.C.) / 2800(O.C.) / 2666(O.C.) / 2600(O.C.) / 2500(O.C.) / 2400(O.C.) / 2200(O.C.) / 2133(O.C.) / 2000(O.C.) / 1866(O.C.) / 1800(O.C.) / 1600 / 1333 MHz memory modules

GIGABYTE - Motherboard - Socket 1150 - GA-Z97M-D3H (rev. 1.1)


For all H97 boards this applies :
* Due to Intel® chipset limitation, DDR3 1600 MHz and higher memory modules on XMP mode will run at the maximum transfer rate of DDR3 1600 Mhz.