Is Linux using only half my ram??

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makeitwork
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Is Linux using only half my ram??

Post by makeitwork » Sun Jan 28, 2018 11:04 am

I recently built a new system and loaded 16GB of RAM sticks as recommended by the manufacturer.

From UEFI, it seems to recognize the RAM, no problem, but if I try "free -m" from the linux command prompt, it doesn't.

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              total        used        free      shared  buff/cache   available
Mem:           7970         925        6020          38        1024        6697
Swap:         40958           0       40958
I'm using x86_64 linux kernel with an AMD CPU Ryzen 7 1700.

With dmi decode, I can see the memory, no problem.

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Handle 0x0017, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x0010
	Error Information Handle: 0x0016
	Total Width: Unknown
	Data Width: Unknown
	Size: No Module Installed
	Form Factor: Unknown
	Set: None
	Locator: DIMM 0
	Bank Locator: P0 CHANNEL A
	Type: Unknown
	Type Detail: Unknown
	Speed: Unknown
	Manufacturer: Unknown
	Serial Number: Unknown
	Asset Tag: Not Specified
	Part Number: Unknown
	Rank: Unknown
	Configured Clock Speed: Unknown
	Minimum Voltage: Unknown
	Maximum Voltage: Unknown
	Configured Voltage: Unknown

Handle 0x0019, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x0010
	Error Information Handle: 0x0018
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 8192 MB
	Form Factor: DIMM
	Set: None
	Locator: DIMM 1
	Bank Locator: P0 CHANNEL A
	Type: DDR4
	Type Detail: Synchronous Unbuffered (Unregistered)
	Speed: 2134 MHz
	Manufacturer: Unknown
	Serial Number: 00000000
	Asset Tag: Not Specified
	Part Number: F4-3200C16-8GTZB
	Rank: 1
	Configured Clock Speed: 1067 MHz
	Minimum Voltage: 1.2 V
	Maximum Voltage: 1.2 V
	Configured Voltage: 1.2 V

Handle 0x001C, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x0010
	Error Information Handle: 0x001B
	Total Width: Unknown
	Data Width: Unknown
	Size: No Module Installed
	Form Factor: Unknown
	Set: None
	Locator: DIMM 0
	Bank Locator: P0 CHANNEL B
	Type: Unknown
	Type Detail: Unknown
	Speed: Unknown
	Manufacturer: Unknown
	Serial Number: Unknown
	Asset Tag: Not Specified
	Part Number: Unknown
	Rank: Unknown
	Configured Clock Speed: Unknown
	Minimum Voltage: Unknown
	Maximum Voltage: Unknown
	Configured Voltage: Unknown

Handle 0x001E, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x0010
	Error Information Handle: 0x001D
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 8192 MB
	Form Factor: DIMM
	Set: None
	Locator: DIMM 1
	Bank Locator: P0 CHANNEL B
	Type: DDR4
	Type Detail: Synchronous Unbuffered (Unregistered)
	Speed: 2134 MHz
	Manufacturer: Unknown
	Serial Number: 00000000
	Asset Tag: Not Specified
	Part Number: F4-3200C16-8GTZB
	Rank: 1
	Configured Clock Speed: 1067 MHz
	Minimum Voltage: 1.2 V
	Maximum Voltage: 1.2 V
	Configured Voltage: 1.2 V
If I use

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lshw -class memory
, I can see it as well

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     *-bank:0
          description: [empty]
          product: Unknown
          vendor: Unknown
          physical id: 0
          serial: Unknown
          slot: DIMM 0
     *-bank:1
          description: DIMM Synchronous 2134 MHz (0,5 ns)
          product: F4-3200C16-8GTZB
          vendor: Unknown
          physical id: 1
          serial: 00000000
          slot: DIMM 1
          size: 8GiB
          width: 64 bits
          clock: 2134MHz (0.5ns)
     *-bank:2
          description: [empty]
          product: Unknown
          vendor: Unknown
          physical id: 2
          serial: Unknown
          slot: DIMM 0
     *-bank:3
          description: DIMM Synchronous 2134 MHz (0,5 ns)
          product: F4-3200C16-8GTZB
          vendor: Unknown
          physical id: 3
          serial: 00000000
          slot: DIMM 1
          size: 8GiB
          width: 64 bits
          clock: 2134MHz (0.5ns)
I read about other people having similar problems but they were due to either running a 32-bit kernel (i have 64) or not having the latest BIOS (I'm using UEFI not BIOS and it is updated to the latest version).


I'm not sure what to try next.

rene
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Re: Is Linux using only half my ram??

Post by rene » Sun Jan 28, 2018 11:20 am

Yes, Linux sees only half your RAM -- and I trust your BIOS ("your UEFI" if you like) also does. dmidecode and lshw are not all that useful as all they do is report what the DIMM themselves report, not what the motherboard sees.

You are listing two 8GiB DIMMs, one in DIMM slot 1 and one in DIMM slot 3 which is an arrangement which might indeed very well not work: try placing them in slot 0 and 2 -- which might be marked 1 and 3 on your motherboard if it counts 1-based rather than lshw/dmidecode's 0-based, but just change slots. Check in your BIOS for the total RAM recognized.

[EDIT] Trouble with supplying useful information such as you did in the sense of lshw and dmidecode listings is that some responders then forget there also was actual text to accompany them; you already said that your BIOS detects the right amount. Still, still try changing slots first.

makeitwork
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Re: Is Linux using only half my ram??

Post by makeitwork » Wed Jan 31, 2018 9:03 am

The BIOS sees the memory as you can see in the attached picture. The memory chips are also exactly in the motherboard according to the manufacturer's specification, as you can see in the two other pictures.
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IMG_2490.JPG
IMG_2489.JPG

Neil Edmond
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Re: Is Linux using only half my ram??

Post by Neil Edmond » Wed Jan 31, 2018 9:18 am

Still, a little troubleshooting isn't going to hurt, and may help you narrow the issue down. Try each RAM module, one at a time, in each RAM slot. If all checks out OK, then try both RAM modules together in various slot configurations. This way you can rule out defective RAM and/or slots. I know, I know, it's new hardware, but there can still be defects.

rene
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Re: Is Linux using only half my ram??

Post by rene » Wed Jan 31, 2018 10:21 am

makeitwork wrote:The BIOS sees the memory as you can see in the attached picture. The memory chips are also exactly in the motherboard according to the
manufacturer's specification, as you can see in the two other pictures.
Good information again. Unexpected, but yes, dual-DIMM seems to indeed need slots A2 and B2 per that (Ryzen) table. Something strange is going on though: according to that same table the memory should be running at either 2667 or "2400-2667" MHz depending on Single/Dual Rank architecture respectively, and certainly it should be running in Dual Channel mode. According to your BIOS screenshot you're running at 2133 Single Channel. That is, Linux is not the only thing having issues...

You can experiment, but I'd take this to mean that the memory and motherboard are in fact likely incompatible; that you'd need different DIMMs.

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ClixTrix
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Re: Is Linux using only half my ram??

Post by ClixTrix » Wed Jan 31, 2018 10:46 am

You need to consider that the Trident Z Series F4-3200C16-8GTZB G.Skill memory you're using is probably NOT Ryzen compatible.

It's not recommended by either AMD on their official list....

https://www.amd.com/system/files/2017-0 ... t-en_0.pdf

....and it's not recommended by G.Skill.

https://www.gskill.us/forum/showthread.php?t=14263

I don't know which ASrock MB you have, but ASrock should have a compatibility list specific to your board. I did check several X370 boards there and don't see your series listed as compatible.

The memory reported by BIOS/UEFI is consistent with what is read from memory SPD. However, the compatibility problem with chips is likely the reason that real usable memory is half.
Linux Mint 18.3 x64 Cinnamon Kernel 4.14.20 Mainline (Ukuu)
Gigabyte GA-AB350M-D3H (F5a) / Ryzen 5 1600 / Micron Ballistix Sport DDR4 2400 2x8GB / XFX HD5450-1GB
NVMe-SSD Samsung EVO 960 250GB / HDD WD1600BEKT 160GB / SSD Toshiba OCZ VX500 512GB

pcwolf
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Re: Is Linux using only half my ram??

Post by pcwolf » Wed Jan 31, 2018 8:25 pm

I have the AsRock Killer SLI/ac board with two 8GB ram modules in the same slots your picture shows.

Ram is Crucial CMU16GX4M2C3000C15 x 2

"free -m" shows all 16GB

Also, manages to run at 2933mhz although memory is also not on the compatibility list.

Mint 18.3 KDE kernel 4.13.0-31 and UEFI 3.20

Another data point, hope this helps. Seems likely to me a bad ram module.

-Phil

makeitwork
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Re: Is Linux using only half my ram??

Post by makeitwork » Sat Feb 03, 2018 6:02 am

I tried swapping the RAM modules and using only 1 of each in the A2 spot. Linux doesn't recognize them together but can use either of them individually. The RAM chips I've been using are F4-3200C16D-16GTZB. The motherboard is an X370 Killer SLI, which supposedly supports this chips at a speed of 2933MHz (http://www.asrock.com/mb/AMD/X370%20Kil ... asp#Memory).

I'm assuming that it's some kind of memory chip/CPU incompatibility. I have ordered a couple of new memory sticks of CMU16GX4M2C3000C15.

Davdi
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Re: Is Linux using only half my ram??

Post by Davdi » Sat Feb 03, 2018 6:12 am

Maybe obvious, but have you tried running Memtest for several hours/overnight (mightn not need to run for very long if one stick is faulty though).
I had similar problems with a Gigabyte Sniper board/Core i7/16GB rig, memtest showed errors in slot 0 after about 10 minutes.
RMA for 2 new sticks (Corsair)
Just stop and think before you click that link.

makeitwork
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Re: Is Linux using only half my ram??

Post by makeitwork » Sat Feb 03, 2018 1:35 pm

I just tried memtest. I let it run for an hour and it found no errors. But it sees only 8MB just like the kernel.

Davdi
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Re: Is Linux using only half my ram??

Post by Davdi » Tue Feb 06, 2018 1:58 pm

Just a thought, have you tried running with each stick individually? A dodgy stick seems most likely. Can you get hold of some other known good RAM to try, just in case the slot on the motherboard is faulty.
Just stop and think before you click that link.

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