Question Windows 10 not using all my RAM

AVeryConfusedPerson

Commendable
Oct 18, 2016
40
1
1,535
So recently I got a new Motherboard, CPU, GPU, PSU, and RAM.
I finished installing everything today and it works just fine. Windows 10 recognized that there is 16gb of ram installed, but it says "16.0 GB (7.46 GB Usable)"
Also when I go into task manager while playing Arma 3, it's saying 85% Memory, but Arma 3 is only using around 4000mb, and everything else is very very small amounts.
My current specs are:
MOBO: MSI B450M PRO-VDH (link)
CPU: AMD Ryzen 5 2600 (link)
RAM: CORSAIR Vengeance RGB 16GB (2x8GB) DDR4 @3000mhz(link)
GPU: PowerColor Red Devil RX 580 8gb (link)
PSU: EVGA 750N1 (link)
 

compprob237

Distinguished
So recently I got a new Motherboard, CPU, GPU, PSU, and RAM.
I finished installing everything today and it works just fine. Windows 10 recognized that there is 16gb of ram installed, but it says "16.0 GB (7.46 GB Usable)"
Also when I go into task manager while playing Arma 3, it's saying 85% Memory, but Arma 3 is only using around 4000mb, and everything else is very very small amounts.
Where is it saying "16.0 GB (7.46 GB Usable)"? There's only been a few times I've come across that and one was from a stick not being recognized + reserved memory for system + reserved memory for iGPU being subtracted from the available amount. Another time was a dialog box for a game I was playing because it complained I didn't have enough usable memory. The last time(s) was an entire channel (Channel B for me) disappearing because the IMC was unhappy with my overclock.

Now, 85% of 7.46 GB = 6.341 (6,493.18MB) so you must have another 2.3GB of RAM used, besides the 4,000MB by ArmA 3, and that's roughly the common idle usage of Windows 10. This leads me to believe that you have an entire stick of memory not being usable by the system. It wouldn't hurt to try re-seating the sticks. You could also take both sticks out and install one in the proper slot (Your's is slot "DIMMA2" for your motherboard). See if it boots with that single stick. If it boots then swap sticks and try again. If you've got a dead stick then booting with only the dead one wont even reach BIOS. If both sticks boot individually then try the sticks, installed in the proper slots (DIMMA2 & DIMMB2), and see if it boots.

As for used memory vs available:
A game will only use as much memory as it's programmed to use. Some limit themselves to a specific amount (4,000MB appears to be ArmA 3's limit) and others dynamically use what's available. This will fluctuate based on the needs of the program. I wouldn't sweat it too much if there's some unused RAM. Heck, I play a game that could easily use up 40GB of RAM if it wanted to (the entire game) but it sticks to ~14GB even though I have 30GB of RAM.
Now, if you're looking at the Memory tab of Task manager then you'll see an additional field inside Memory composition titled "Standby". This is usually cached data that Windows is using for other system files. These files are unnecessary to the actual RAM use so they're just there to use the fast RAM and speed up system performance.
Then there's "Committed". This value is actually your total RAM capacity + any and all page files combined. The left side of the fraction is the total virtual memory load on the system and the right side is the total available virtual memory pool. This value is actually misleading because it is how much memory is requested of the system but is not exactly what the system is using.