i7 6700K won't POST when DDR4 set to 2400Mhz

May 29, 2018
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Memory: 2x HyperX Fury Black 16GB 2400Mhz set in Dual Channel mode
Motherboard: ASUS B250M-A
CPU: Intel i7 6700K

I previously had an i5 7500 CPU and swapped to an i7 6700K. On the previous CPU, selecting the XMP profile for memory would run it at 2400Mhz. Once I swapped to the i7 processor, even with the XMP profile on and BCLK FSB: DRAM ratio 100:133, memory remains at 2133. I tried setting RAM voltage to auto, still nothing. Finally there is also an option to select memory speed manually. If I set it to anything above 2133, the system won't POST. Anything at or below that works.

It should be noted that on the i5, setting memory to 2400 from that same option would also produce a non-booting system, and enabling the XMP profile while leaving memory frequency on auto would correctly configure the system to run the RAM at 2400Mhz.

What am I doing wrong here?
 
Solution
I understand that the CPU's FSB is 2133 and that my previous CPU had a 2400 FSB but just about everywhere I looked online so far, there was nothing saying I shouldn't be able to run the memory at 2400 with a 2133 CPU. I even have the CPU: DRAM ratio setting, which also appears to do nothing.
Yes, the i7 6700K can support up to 2133mhz https://ark.intel.com/products/88195/Intel-Core-i7-6700K-Processor-8M-Cache-up-to-4_20-GHz and the new i5 will support up to 2400mhz https://ark.intel.com/products/97123/Intel-Core-i5-7500-Processor-6M-Cache-up-to-3_80-GHz Because your used the B250M MB so that you can't oc the RAM or CPU. Just run the RAM at 2133mhz with i7 6700K, nothing you can do. Sorry.
Between my last BIOS and the latest BIOS update(latest was released this very month!) there were a number of mentions of stability improvements and memory compatibility fixes. Unfortunately after the update the issue persists in the same manner. Activating XMP profile - which was the only way I could get 2400Mhz out of it on the i5 - does nothing on the i7.

Usually, the preview in the top left of target frequencies shows when you are about to change frequencies as a result of settings changes. And in this case it simply does not. They remain the same even after I select XMP. The only time it ever changes to 2400 is when I manually specify the frequency in a later option, and as I mentioned after committing those settings and restarting, the system refuses to POST.

I understand that the CPU's FSB is 2133 and that my previous CPU had a 2400 FSB but just about everywhere I looked online so far, there was nothing saying I shouldn't be able to run the memory at 2400 with a 2133 CPU. I even have the CPU: DRAM ratio setting, which also appears to do nothing.
 
I understand that the CPU's FSB is 2133 and that my previous CPU had a 2400 FSB but just about everywhere I looked online so far, there was nothing saying I shouldn't be able to run the memory at 2400 with a 2133 CPU. I even have the CPU: DRAM ratio setting, which also appears to do nothing.
Yes, the i7 6700K can support up to 2133mhz https://ark.intel.com/products/88195/Intel-Core-i7-6700K-Processor-8M-Cache-up-to-4_20-GHz and the new i5 will support up to 2400mhz https://ark.intel.com/products/97123/Intel-Core-i5-7500-Processor-6M-Cache-up-to-3_80-GHz Because your used the B250M MB so that you can't oc the RAM or CPU. Just run the RAM at 2133mhz with i7 6700K, nothing you can do. Sorry.
 
Solution