Question I have a 64 GB RAM (8 x 16 GB) system but PC System Information shows Installed Physical Memory (RAM) 48.0 GB

Jan 10, 2022

I had a PC custom built for me with the following specification

Components list:
1x Cooler Master CM 690 III Windowed Case - Black
1x Noctua NH-D15 CPU Cooler
4x 16 GB DDR4 2133 MHz Memory
1x NVIDIA GeForce GTX 1080 8GB Graphics Card
1x 250GB Samsung 960 EVO M.2 PCIe Solid State Drive
1x 1TB Samsung 850 EVO Solid State Drive
1x RAID 1 Configuration - Choose 2 identical hard disks
1x Windows 10 Home 64-bit
1x 5 Year Warranty, 2 Years Collect & Return UK only*
1x Intel Core i7-7820X CPU, 8 Cores, 3.6 - 4.3GHz
1x Asus PRIME X299-A Motherboard
2x Seagate 1TB BarraCuda 7200RPM Hard Disk
1x Corsair RM850x 80 PLUS Gold 850W PSU
As you can see this system should have an installed physical DDR4 memory of 64 GB (8 by 16 GB DDR4 sticks).

However, upon checking the 'System Information' in the Control Panel the following is listed instead - see pasted information below.

Am I to assume, according to the 'system information' listed here, which has a listed 'Physical Memory' of only 48GB, that therefore either one of the 16 GB sticks was not properly placed in the appropriate port when this PC was built? Which is why it is showing as 48GB and not 64GB with 16 GB not registering within the system ? In which case, could such a problem now make the system unstable? Would be good to know if anyone can advise!

Or, could it mean when this PC was built, the manufacturers, who I have used before and who are normally very good I have to say, perhaps still simply forgot on this occasion to put in the 4th 16 GB stick.

Or, is this discrepancy entirely normal and nothing to be concerned about and so it means that I still have 64 GB on this system and not 48 GB physical RAM it is showing me.

Grateful for any advice.

PLEASE NOTE: I know some discrepancies can exist when, for example, some of the installed physical memory may be reserved for certain components, like my GPU for instance, but I was still thinking even if this does happen and even if it is the case here, wouldn't all this do is simply mean the 'Available Memory' might now be listed at less than the 64 GB; but would I still not expect the 'Physical Memory' to still be listed at the 64 GB if that is what has been actually installed in this system after all; right?

My System Information report written at: 12/26/21 15:46:54
[System Summary]

Item Value
OS Name Microsoft Windows 10 Home
Version 10.0.15063 Build 15063
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name DESKTOP-HJ0P535
System Manufacturer System manufacturer
System Model System Product Name
System Type x64-based PC
System SKU SKU
Processor Intel(R) Core(TM) i7-7820X CPU @ 3.60GHz, 3601 Mhz, 8 Core(s), 16 Logical Processor(s)
BIOS Version/Date American Megatrends Inc. 0503, 11/07/2017
SMBIOS Version 3.0
Embedded Controller Version 255.255
BaseBoard Manufacturer ASUSTeK COMPUTER INC.
BaseBoard Model Not Available
BaseBoard Name Base Board
Platform Role Desktop
Secure Boot State On
PCR7 Configuration Binding Not Possible
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume5
Locale United Kingdom
Hardware Abstraction Layer Version = "10.0.15063.909"
Username DESKTOP-HJ0P535\amer farhan
Time Zone GMT Standard Time
Installed Physical Memory (RAM) 48.0 GB
Total Physical Memory 47.7 GB
Available Physical Memory 41.8 GB
Total Virtual Memory 54.7 GB
Available Virtual Memory 48.5 GB
Page File Space 7.00 GB
Page File C:\pagefile.sys
Device Encryption Support Reasons for failed automatic device encryption: TPM is not usable, PCR7 binding is not supported, Hardware Security Test Interface failed and the device is not InstantGo, Un-allowed DMA-capable bus/device(s) detected, TPM is not usable
Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualisation Enabled in Firmware Yes
Hyper-V - Data Execution Protection Yes


Win 11 Master
64 GB (8 by 16 GB DDR4 sticks).
8 x 16 = 128
4x 16 GB DDR4 2133 MHz Memory
difference appears to be 1 stick. Have you run memtest? Easier way would be just swap ram out and see which one doesn't show. then run memtest on it. save time with 4 sticks.

Try running memtest86 on each of your ram sticks, one stick at a time, up to 4 passes. Only error count you want is 0, any higher could be cause of the difference. Remove/replace ram sticks with errors.
Memtest is created as a bootable USB so that you don’t need windows to run it