Hello Graycat, thanks for contacting us through the Intel Communities and for choosing our products.
It is important to know that the i7-4790K supports by default memory speeds of 1333MHz and 1600 MHz (max). This is an unlocked processor which could handle higher memory speed by either manually setting or by using an XMP profile.
Bear in mind that XMP profiles were created for easy over clocking the memory so the user only picks a profile type with no need to go through changing speeds, multipliers and voltages. So if the motherboard offers XMP profiles faster than 1600MHz, be aware that this is a direct overclocking to the Memory Controller Hub (MCH) in the processor which could represent eventually possible stability problems.
In regards of the memory models you quoted I could recommend using the one that runs at 1600MHz via SPD.
Intel provides unlocked processors so that customers who are interested in overclocking may do so, but please be aware of the following:
- Overclocking voids your standard processor warranty. Intel encourages customers to consider purchasing an Intel® Performance Tuning Protection Plan (PTPP) if they chose to overclock their processor. The PTPP provides warranty coverage for most overclocking scenarios. The details on the PTPP are available at http://click.intel.com/tuningplan/
- Intel does not guarantee that a processor will be able to achieve any specific speed when overclocked.
- Intel will not be able to advise or assist customers with the overclocking process. Please consult your desktop board manufacturer on recommended system settings.
I have used GSkill F3-2400C11Q-32GXM RipjawsX selected from Gigabytes memory QVL for the GA-Z97MX Gaming 5 mobo with an i7-4790K.
SPD is 1333 but XMP at 2400 worked without a problem and memory runs at its specified speed without faults (tested in memtest86+ for 6 passes of 32Gb).
Was pleasantly surprised !
Hope that helps.