Asus Sabertooth X99 only recognize 6 out of 8 DIMMs in XMP mode

I have a brand new Saberbooth X99 motherboard with an i7-5820K processor installed.

Also, I have the following memory installed:

G.SKILL Ripjaws 4 series 64GB (8 x 8GB) 288-Pin DDR4 SDRAM DDR4 2666 (PC4-21300) Memory Kit Model F4-2666C16Q2-64GRB
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231831

Initially entering the BIOS for the first time, I see 8 DIMMs being recognized with a total memory count of: 65536 MB (64 GB) @ memory frequency of 2133 MHz.

Problem: After enabling XMP mode, BIOS will automatically raise MB base clock from 100 MHz to 125 Mhz, which I believe is normal. But now the BIOS only recognize 6 out of 8 DIMMS. In the first 6 slots, it states "G-Skill 8GB 2133MHz". But in the last 2 slots it states "N/A". Why?

* Addendum: I should also mention that I just opened a case about this issue with Asus tech support. They have requested that I do the following before they proceed: Take each of the 8 memory, and place in each of the 8 slots to verify that the memory isn't at fault. That is 64 combinations! I personally don't think that's a reasonable request, but I'm open to your interpretation.
 
Check for the latest BIOS, or request it directly from ASUS.

What version/date do you have? There are updates that may improve compatibility.

To test the RAM, have one module installed at a time in the initial A1 slot with XMP enabled to see if they all recognize and operate smoothly on their own. If they all work individually, try two or three modules in the N/A slots to see if they show up or if they show up as 8GB out of 24GB. This helps give us an idea of what may be causing the issue.

 
First of all, thank you for responding to my forum post.

Yes, I've indeed updated to the latest BIOS on the Asus Sabertooth X99; v1801 released on 5/15/15.

Slots DIMM_D1 and DIMM_D2 are the ones that show "N/A". I find it very strange that those two slots appear to recognize the memory okay, until after I enable XMP mode. I will take the steps that you've listed.
 

Inyobase

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Any update to your issue? I'm running into the same issue but with corsair vengeance lpx 32gb. Same dimm show na.




 
@Inyobase

Yes, I have an update and the resolution of my issue. First of all, thank you a million times over for appending to this thread. I wanted to update it, but I honestly couldn't find it. I respond to over 100 message threads a month and honestly couldn't find this one.

The solution came from Asus tech support. The g.skill memory that I purchased was not on the Asus Sabertooth X99 "Qualified Vendor List" for 64 GB of memory. This appears to be mostly an issue if you're attempting to run 64 GB (eight 8 GB dimm modules) on an X99 board, however it can also be an issue with 32 GB of installed memory. The QVL will tell you precisely if that's the case. It's not a fault of G.skill, as there were only 12 specific models (not brands) of memory that supported this. And of the 12 models, I believe only 4 model numbers were available, but don't quote me.

*** Steps to find QVL (Qualified Vendor List) for your Asus motherboard ***

Google: sabertooth x99 ->

Google result: Motherboards | SABERTOOTH X99 | ASUS USA SABERTOOTH X99 - Overview

<click> Support
<click> Memory/Device Support
<click> X99 Series DRAM QVL

@Inyobase, please let me know if you need a more detailed explanation.

Addendum:

For the record, I returned this memory (immediately below) to NewEgg minus a 15% restocking fee that they charged me because it was purchased over 30 days before:

G.SKILL Ripjaws 4 Series 64GB (8 x 8GB) 288-Pin DDR4 SDRAM DDR4 2666 (PC4 21300) Memory Kit Model F4-2666C16Q2-64GRB
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231831

And I purchased this memory (below)

CORSAIR Vengeance LPX 64GB (8 x 8GB) 288-Pin DDR4 SDRAM DDR4 2400 (PC4 19200) Memory Kit Model CMK64GX4M8A2400C14
http://www.newegg.com/Product/Product.aspx?Item=N82E16820233734

* I was able to successfully enable XMP mode, which raised my motherboard's base clock from 100 MHz to 125 Mhz, and all eight DIMMs were registering at the rated speed. My new Corsair memory is rated at only 2400 Mhz, as opposed to the g.skill's 2666 Mhz, but I honestly don't care. I'm just glad that my build is now stable. FYI: I haven't overclocked my CPU yet because I simply haven't gotten around to it and it's been fast enough for me.
 

Inyobase

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So on the qvl only the ram that has a dot in the last column for 8dimms will work with 64? I have the CMK32GX4M4A2666C16 ram bought 2 sets of 32, does this mean I should buy the ones you got? Thank you for taking the time to respond I'll keep an eye on the thread since having 48 gigs instead of 64 is driving me nuts
 
The way I'll word my answer is "Only the RAM listed in that column of the QVL table is tested and certified by Asus to properly register all DIMM modules." Is the Sabertooth X99 the precise board that you own? If so then my memory is a great choice because it's reasonably priced. I just simply copy and pasted all the model numbers into the NewEgg search field and checked the prices. Back in August or September, the memory I bought was the only reasonably priced option.

No problem. Feel free to keep responding to this thread, PM me, or both. It's extremely frustrating to spend all the money on memory and not have it work right. I've been where you are. Trust me.
 

Inyobase

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Correct, I'm sitting on the same board and processor as you. You've been a great help with keeping my sanity intact. I bought the same kit as you and requested a return from Amazon for the 2 32gig kits. The ram was a little cheaper at Newegg but I dislike their return process. Ram should be in tomorrow and hopefully will solve the issue.
 
Please let me know how it goes. I found this issue to be incredibly stressful, since I bought the memory for a new build and spent $600 on the original g.skill memory and about $500 for the replacement Corsair. Plus, in addition to gaming, this computer is used for my VMware lab, so having only 48 GB available out of a 64 GB kit was not acceptable. VCops (pronounced vee-cee ops) alone requires a minimum of 48 GB to operate. Ideally I would have preferred having 128 GB installed, but I have budgetary constraints just like everybody else. Eight 16 GB DIMMS, plus an E5 v3 Xeon processor, starts to look like real money, real fast. This was my poor man's build, so to speak.

- Rob
 

Inyobase

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I'll keep you posted as soon as I put the ram in my system. My setup is mostly for gaming but I would like to run some sort of virtual lab setup but not too familiar with the VCops program you mentioned. May I ask what your purpose for it is? I would like to set up practice lab for the MCSA/MCSE Certification. Quite honestly though I maxed out my system because I have a mild compulsion to fill all my ram slots,
Just a small OCD. Hehe
 

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