32Gb Ram Installed, Only 15.973 GB Useable


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Hi all,

 

I've had this on-going issue for a while now and i cant seem to get my head round it. Recently i bought an extra 16GB of Hyper X Fury ram which is already installed in the machine. Same model so no compatibility issue. I installed the first set in and had the issue in the subject line. A few restarts later and still no luck.

 

I then asked for it to be replaced, assuming faulty RAM. Again, the same issue.

 

The current setup is as followed:

 

Ryzen 2700

Aorus x470

32GB Hyper X Fury DDR4 2400Mhz

Unraid 6.6.7

MSI GeForce GT 710

 

Unraid sees the RAM, as 32GB installed, it just advises only 16GB is useable.

 

image.png.ca3b925a25f7afff8e3ec04e71c95458.png

 

Any help would be greatly appreciated.

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15 minutes ago, jonathanm said:

Sounds to me like a motherboard BIOS setting, or possibly dual channel mode trying to initialize but the sticks are in the wrong slots.

 

Check the motherboard manual and see if pairs of memory are supposed to be in adjacent or opposite slots.

The motherboard only has 4 slots, which are all populated. Looking at the manual it states that when all 4 are populated the motherboard automatically switches to dual channel mode.

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Are all 4 modules the exact same configuration? Just because they have the same part number doesn't mean the chips on the modules all match.

 

From what I'm seeing in google, your symptoms are a motherboard setting or memory compatibility issue. Each stick by itself is probably perfect, but trying to get all 4 to run together in dual channel mode properly can be problematic.

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1 minute ago, jonathanm said:

Are all 4 modules the exact same configuration? Just because they have the same part number doesn't mean the chips on the modules all match.

 

From what I'm seeing in google, your symptoms are a motherboard setting or memory compatibility issue. Each stick by itself is probably perfect, but trying to get all 4 to run together in dual channel mode properly can be problematic.

Should i try running an ubuntu session from a USB stick and see if it utilizes 32gb ? If it does, would that not signify that Unraid is the problem?

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43 minutes ago, Zyluphix said:

Same model so no compatibility issue.

You sure it's compatible?  Always, always check the QVL for the motherboard prior to buying memory.  That motherboard has quite a number of HyperX p/n's that are not compatible in a 4 stick configuration.

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2 minutes ago, Squid said:

You sure it's compatible?  Always, always check the QVL for the motherboard prior to buying memory.  That motherboard has quite a number of HyperX p/n's that are not compatible in a 4 stick configuration.

I think you've got it.

 

HyperX HX424C15FB2K2 is not compatible in 4 slots. Damn. I looked up the wrong part number originally!

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I had a similar problem a few years ago, where unRaid wouldn't recognize the extra memory, Windows wouldn't etc.  The BIOS would report the total though.

 

Since then I only ever buy from the QVL and if expanding and the original sticks are no longer available I either buy a whole new set or make damn sure that at the very least the additional set is listed on the QVL and at the very least has the same CL timing.

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Just now, Squid said:

I had a similar problem a few years ago, where unRaid wouldn't recognize the extra memory, Windows wouldn't etc.  The BIOS would report the total though.

 

Since then I only ever buy from the QVL and if expanding and the original sticks are no longer available I either buy a whole new set or make damn sure that at the very least the additional set is listed on the QVL and at the very least has the same CL timing.

That's a killer. Well I think my cheapest option is to get a motherboard that's compatible. Now i just need to do that hunt!

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  • 4 months later...
1 hour ago, MajorArchitect said:

I have 96gb installed 4x8GB and 4x16GB. my issue is similar in that it only shows 32GB in unraid as usable and installed, in Windows 10 everything works PERFECT all 96GB show, but 64GB of the ram is missing in unraid 6.6.6 or 6.7.2

Try a different live USB distro like linux mint.

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2 hours ago, MajorArchitect said:

I have 96gb installed 4x8GB and 4x16GB. my issue is similar in that it only shows 32GB in unraid as usable and installed, in Windows 10 everything works PERFECT all 96GB show, but 64GB of the ram is missing in unraid 6.6.6 or 6.7.2

Just because Win10 reports that all 96GB is seen doesn't mean all 96GB is accessible. Did you try consuming more than 32GB of memory while in Win10?

I'd at least run memtest86 for a full pass if it sees 96GB.

  • Upvote 1
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in short, yes, I used way beyond 32GB in windows. I didn't get to trying a different distro of Linux. HOWEVER I did get it to work in unraid by moving the 16GB modules from channels C and D to A and B. I did one start with just the 16GB modules saw 64GB then put the rest back in and have 96GB in unraid. Kind of strange because I reseated it twice the way it was and it didn't work. It looks like somewhere something didn't like the 16GB modules being in channels C and D. May have to do with my motherboard and how it reported the modules to unraid. For reference the Mother Board is a Gigabyte x99P-SLI and  it is worth noting that some gigabyte boards (this included) are known to have strange issues where trident z RGB memory does not show on half of the channels in the LED software and it is unable to modify the SPD data on the RAM. although I have trident Z, the 16GB DIMMs are NOT-RGB. 

 

So in hindsight maybe this belonged on another topic but it may still help people if they have a similar issue.

 

(Edit)

I just noticed the original post also used a Gigabyte board as well. And although people concluded it looked like the memory modules that weren't compatible based off the QVL, some people may have something else happening. Someone mentioned configuration before, in my case it didn't even want to post if a 16GB dim was in the same channel as a 8GB (understandable, just saying); And then the issue I had where moving memory channels fixed it. So making sure that they match based off of what channels they are in may matter, and even then toying with what is in which channel may help. 

Edited by MajorArchitect
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On 7/31/2019 at 3:20 PM, MajorArchitect said:
On 3/14/2019 at 8:18 PM, jonathanm said:

I'm positive unraid isn't the problem.

I have 96gb installed 4x8GB and 4x16GB. my issue is similar in that it only shows 32GB in unraid as usable and installed, in Windows 10 everything works PERFECT all 96GB show, but 64GB of the ram is missing in unraid 6.6.6 or 6.7.2

If you read what I posted through this thread, you would have seen where I said...

On 3/14/2019 at 8:14 PM, jonathanm said:

your symptoms are a motherboard setting or memory compatibility issue.

which is exactly what you found.

3 hours ago, MajorArchitect said:

It looks like somewhere something didn't like the 16GB modules being in channels C and D. May have to do with my motherboard

 

Linux in general is more picky about hardware, or to be more accurate, hardware vendors spend much less time making sure their products are compatible with linux than windows. Something that "just works" in windows may very well have issues in linux. Unraid doesn't author the linux kernel they use, they just package it.

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