16 Gigs but why does it show less than 16 Gigs on System info

[Amenophis]

I was looking at the following Laptop at Staples recently. Here's the unit ...
ASUS ROG Strix GL753VD 17.3" Gaming Laptop, 2.8 GHz Intel Core i7-7700HQ, 1 TB HDD, 16 GB DDR4, NVIDIA GeForce GTX 1050, Win10

My question is this. I notice it has an independent video card with 16 Gigs of sheep, I mean RAM. Looking at the specs on the machine itself, I notice it says it has 16 Gigs of RAM but then it says 15:8 (or something close to that figure but less than 16 Gigs).
My question is ... why does it say in Windows Setttings / About ... it has less than the 16 Gigs of RAM it is supposed to have. I thought only integrated graphics did that. Please advise.

[Monkburger]

This is caused by PCI Address Mapping from Devices into the system memory.

It's completely normal, though.

[Amenophis]

Why does one ASUS do this and another one does not? I'm talking about three ASUS that were on the shelf at Staples and two did not show 15.6 or whatever that number was ... they just showed a straight 16 Gigs of RAM. But the one that has the 16 Gigs of sheep, well, there I go again, I mean RAM shows the 15.6 or 15.8.

[Monkburger]

This depends on numerous things

- Onboards Graphics memory allocation
- PCI cards (PCI-E) - Some devices will allocate 64MB of PCI memory for say, audio streams or RAID configurations. (software raid may do this) - Please see https://social.technet.microsoft.com/Forums/getfile/437642
- Memory remapping (aka memory hole enabled/disabled)

[Amenophis]

Thank you for the helpful reply. Much appreciated!