Question 16gb of ram only 7.93gb usable

Jun 11, 2019
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Hello, I recently built a new computer with 16 gb of DDR3 memory (4 x 4) clocked at 1333MHz. Even though I have 16gb of RAM, only 7.93 is usable. Task manager is telling me 8.1gb is hardware reserved. I've tried unchecking the Maximum memory box in msconfig, I've updated my BIOS (I had outdated BIOS apparently), and I've set the RAM back to its core clock (I had overclocked to 1920MHz). Nothing has worked. Thanks in advanced to anyone that can help me.

My specs:
Intel Xeon X3440 2.53GHz
Intel DH55TC motherboard
16gb of Micron DDR3 RAM dual channel
Nvidia GeForce GT730
240gb Patriot Burst SSD
250gb Seagate HDD
Apevia 450 watt power supply
 

boju

Champion
What does bios say how much ram you have?

In cases such as this it is often memory not completely compatible with each other. Were the four sticks bought as a kit or a mix?

Try two sticks and alternate between them trying different combinations.

Were four sticks installed intially first of? If two sticks were an add-on, try load bios defaults incase bios hasn't configured for four dimms properly.
 
Jun 11, 2019
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What does bios say how much ram you have?

In cases such as this it is often memory not completely compatible with each other. Were the four sticks bought as a kit or a mix?

Try two sticks and alternate between them trying different combinations.

Were four sticks installed intially first of? If two sticks were an add-on, try load bios defaults incase bios hasn't configured for four dimms properly.
Bios says I have 16384Mb (16gb) of RAM, and the RAM sticks are all Micron 4gb sticks all clocked at 1333MHz, but they weren't all bought as a kit. They were both 4gb x 2 kits, but they are both made by Micron. Originally I had just 1 8gb kit and I had the same problem, only 3.93gb usable, so I thought I'd try and buy more to see if that would help. Then I bought the second kit and installed it, and that's when I got the same issue: 16gb, only 7.93 usable. So I tried your suggestion: try each pair. Both pairs gave me 3.93gb usable. So then I went into BIOS and pressed f9 to reset all the settings to default. Booted up the computer and still 7.93gb usable. Then I tried the sticks individually. All of them work by themselves. What else is there to do?

Thanks for your feedback
 
Jun 11, 2019
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Boot the computer with one RAM stick at a time to rule out any faulty RAM.

Are all the RAM sticks the same? Is this a fresh installation of Windows?
This is a brand new installation of Windows 10 pro, and all the RAM are Micron 4gb sticks clocked at 1333MHz. Each stick works individually.

Thanks for you feedback
 
Jun 11, 2019
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Jun 11, 2019
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Try booting with single ram module. Try all ram slots this way.
I said earlier I tested all of then individually and they all worked. I can't try all the RAM slots with just one stick because I have to have 1 stick in the first DIMM 0 slot or else the motherboard alarm will go off. It even says in the manual "always occupy the DIMM 0 slots first"

Thanks for the feedback
 

boju

Champion
Motherboard isn't liking all memory sticks together. Hard to tell unless you had a kit of four sticks to try or go for 2x 8GB.

After bios update, did you clear cmos so the new system parameters and micro codes from the new bios file refreshes into cmos?
 
I said earlier I tested all of then individually and they all worked. I can't try all the RAM slots with just one stick because I have to have 1 stick in the first DIMM 0 slot or else the motherboard alarm will go off. It even says in the manual "always occupy the DIMM 0 slots first"
Ok .. then try with 2 ram modules.
Module #1 in DIMM0 and module #2 - alternate between rest of the slots. 3 possible combinations this way.
This should give you info, which slots are usable.

Also - inspect cpu socket for bent pins.
 
Jun 11, 2019
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Motherboard isn't liking all memory sticks together. Hard to tell unless you had a kit of four sticks to try or go for 2x 8GB.

After bios update, did you clear cmos so the new system parameters and micro codes from the new bios file refreshes into cmos?
I actually don't know how to clear cmos, but I have a basic understanding of what it is. Could you tell me how I could clear that?
Also something that I should mention is that, when I reset the motherboard BIOS settings, I had to go back in and enable UEFI boot because Windows won't work without it enabled. 2nd thing I should mention is that even though I have all Micron RAM sticks, all clocked at the same speed, the 2nd pair I bought were slightly different than the first pair. The original pair (the first pair) had memory chips on both sides, but the second pair, even though they had the same amount of RAM as the previous, only has memory chips on one side.

Thanks for the feedback
 

boju

Champion
Yes you're right about loading or resetting bios/cmos will have to configure bios boot options again.

To clear cmos is either use the jumper which the procedure should be mentioned in the manual. Or you can remove the button battery. Both ways require to power off pc as you would have known. Short clear cmos pins with jumper or screw driver. If remove battery, disconnect power cord, hold case power button to drain remaining power from capacitors. Then remove the watch sized button battery from motherboard for a minute or so. Remember which side the battery sits.

Being that the ram is a mixture of single sided and double sided ram is most likely the problem.
 
Reactions: gskill support
Jun 11, 2019
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Ok .. then try with 2 ram modules.
Module #1 in DIMM0 and module #2 - alternate between rest of the slots. 3 possible combinations this way.
This should give you info, which slots are usable.

Also - inspect cpu socket for bent pins.
I put one stick in DIMM 0 Channel A, and one stick in DIMM 1 Channel A, when I did that I got 7.9gb usable. When I tried it with DIMM 0 Channel A + DIMM 1 Channel B, it didn't detect even detect the stick in DIMM 1 Channel B. I thought I maybe didn't put it in correctly, so I tried again, but still it only detected one stick, even in BIOS. I don't think that slot is faulty though because when I have all 4 sticks in, it detects all the sticks. Then when I put it in DIMM 0 Channel A and DIMM 0 Channel B, it detected 8gb but only 3.93 usable.
 
Inspect cpu socket for bent pins.

Also check, if your ram modules correspond to x8 organization.
Support for non-ECC, unbuffered, single-sided or double-sided DIMMs with x8 organization.
16 GB maximum total system memory (with 2 Gb memory technology)
https://www.intel.com/content/dam/support/us/en/documents/boardsandkits/desktop-boards/H55_P55/DH55TC/DH55TC_ProductGuide01.pdf

https://www.micron.com/products/dram/ddr3-sdram/part-catalog?Value=4Gb&Id={826DD0CE-31A2-43CD-AA36-E65D0DB21D31}
 
Jun 11, 2019
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Yes you're right about loading or resetting bios/cmos will have to configure bios boot options again.

To clear cmos is either use the jumper which the procedure should be mentioned in the manual. Or you can remove the button battery. Both ways require to power off pc as you would have known. Short clear cmos pins with jumper or screw driver. If remove battery, disconnect power cord, hold case power button to drain remaining power from capacitors. Then remove the watch sized button battery from motherboard for a minute or so. Remember which side the battery sits.

Being that the ram is a mixture of single sided and double sided ram is most likely the problem.
I turned off then unplugged the power supply, after I held the power button until the motherboard light completely stopped blinking and I held it 5 more seconds just to be safe. I take the motherboard battery out, then 10 minutes later I put it back in, put everything back together, double checked some things, then start it up. BIOS detects all 16gb of RAM but still only 7.93gb usable.

Something I did notice though is that when I have all 16gb of RAM or 8gb dual channel in the computer, Task Manager tells me that I have 4gb of shared GPU memory, but when I have 4gb or 8gb single channel my GPU only has 2gb of shared memory. Could this be relevant to the situation?

View: https://imgur.com/a/FbXgbiU

Thanks for the feedback
 
Last edited:

boju

Champion
Xeon's don't have igpu afaik. The system is saying vram reserved incase you did have a cpu with igpu but probably wouldn't be used in that way. Basically means the motherboard can't address all ram properly and tells Windows it's reserved for hardware. How Windows recognises where the ram is reserved for might not be accurate.

Have you tried placing ram as follows,

Ss | ds | ss | ds

Or

Ds | ss | ds | ss

Ss = single sided chips
Ds = double sided chips
 
Jun 11, 2019
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I believe mt8ktf51264az-1g6e1 (the first link) has x8 organization and
mt16jtf51264az-1g6m1 has x8 organization also I think

2nd pair of RAM, I put a link if you wanted to double check:
https://www.micron.com/products/dram-modules/udimm/part-catalog/mt8ktf51264az-1g6

Original pair of RAM, here is the link if you would like to double check my findings: https://media.digikey.com/pdf/Data Sheets/Micron Technology Inc PDFs/MT16JTF_64AZ_Rev2013.pdf

Also I’m gonna inspect my CPU socket if everything else fails because it was a pain getting the Arctic Cooler 12 backplate to fit. It said it supported lga 1156 sockets but the backplate just barely reaches the screw holes. I’m suprised I didn’t brake my motherboard from all the force I exerted on it. In the end, I somehow got it to work.

Thanks for the feedback
 
Last edited:

molletts

Distinguished
Jun 16, 2009
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Just a thought to add another data-point... Have you tried running Memtest86? If that can see and test all 16GB successfully then at least that more or less rules out a problem with the hardware and points to a software issue with Windows' handling of the hardware.
 
Reactions: boju
Jun 11, 2019
15
0
10
0
Xeon's don't have igpu afaik. The system is saying vram reserved incase you did have a cpu with igpu but probably wouldn't be used in that way. Basically means the motherboard can't address all ram properly and tells Windows it's reserved for hardware. How Windows recognises where the ram is reserved for might not be accurate.

Have you tried placing ram as follows,

Ss | ds | ss | ds

Or

Ds | ss | ds | ss

Ss = single sided chips
Ds = double sided chips
I've tried:

Ss | Ds | Ss | Ds
Ds | Ss | Ds | Ss
Ss | Ds | Ds | Ss
Ds | Ss | Ss | Ds

and still 8.1gb is hardware reserved, and 7.93gb usable. Something I did notice while testing is that, when I'm running the sticks in Single channel (4 x 2), for example:

Ss | Ss | Empty | Empty
Ds | Ds | Empty | Empty

Only 66mb is hardware reserved, or when I'm running the sticks completely by themselves only 33mb is hardware reserved

When I put the RAM in like this:

Ss | Ds | Empty | Empty
Ds | Ss | Empty | Empty

I get 7.9gb usable, which sounds correct, but my computer detects 16gb when only 8gb are installed. Windows and BIOS and CPU-Z say that 16gb are still in the system, but that's false.
 
Last edited:
Jun 11, 2019
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Just a thought to add another data-point... Have you tried running Memtest86? If that can see and test all 16GB successfully then at least that more or less rules out a problem with the hardware and points to a software issue with Windows' handling of the hardware.
Here's my memtest results:

Clk/Temp : 2527 Mhz / 51 C
L1 Cache : 64K 45.67 GB/s
L2 Cache : 256K 24.99 GB/s
L3 Cache : 8192K 21.04 GB/s
Memory : 8182M 7329 Mb/s
 

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