X99 Taichi only seeing 32gb of 64gb quad ch ram

Thank you for this list of great advice, I will give it all a shot and report back soon!

wardog wrote: The serial numbers across all four sticks, are they numbered consecutively?

I am inclined to agree with you that it may be the CPU. The telling detail in that CPUz screenshot is the "dual channel" rather than "Quad Channel" under "Channel #". The fact that the RAM is being detected means it is unlikely the slots themselves which is typically what is wrong when the board is at fault.

I RMA'd the CPU ... that was the issue, I put an i7 6800k in and it worked fine right away. 

swdluxxer wrote: Hi    i will help to to everyone wo will use more as 16 Gb of Ram at Ram Speed more as 2400.   1. Go to Bios and find  "FIVR Configuration" 2. Find and set  your "System Agent Offset" to "0.0300" 3. Save Bios and Restart your Computer.   now you can use more as 16Gb of Ram at higher Speed like 2666 And more, without any Problem. To ASRock - please make it easy for everyone at next Bios Update for X99 Boards and set this "Offset" automaticaly a little bit higher if Mainboard have detect more Ram at higher Speed like a 2666+     Have a nice Day, your swdluxxer

While you are basically correct about adjusting the System Agent (SA) voltage to help with higher speed DDR4 memory, unlike DRAM voltage, more SA voltage is not always better.

Note I did not say more SA voltage is never better, it obviously is in your case. I'm saying there is an appropriate amount of SA voltage, and too much can even have a negative affect.

Actually what you suggested, automatically setting a higher SA voltage is exactly what mother board manufactures and DDR4 manufactures have done with the Intel Skylake platform. The DDR4 memory's XMP data now has much higher SA voltage levels, 1.2V or more. The mother boards, when SA voltage is set to Auto SA voltage and manually setting a higher memory speed will also set a higher SA voltage. I've seen an Auto SA voltage of over 1.2V on my Skylake board.

But I have found that these high SA voltages are not always necessary. That is my point, there is a sweet spot for SA voltage that depends upon the memory being used, and the memory controller, which is part of the CPU.  I can manually set the SA voltage to 1.1V at the same memory speed, and it works fine. It's difficult to know the exact SA voltage when you are dealing with offsets in the UEFI settings, but if you try different monitoring programs like AIDA64, HWiNFO, etc, you can find it.

Thanks for your tip and feedback about what works for you, that is valuable to users and ASRock.