Question Memory Usage higher than Physical RAM being used

[Mechanics55]

Hey guys,
I know there have been multiple posts on this question. I've viewed most of them and still can't sort my issue.
I have 8GB of RAM (I did have 16 but one of my RAM slots died on the mb so my PC wouldn't boot) and even if barely any processes are being used the computer lists the memory usage really anywhere from 30-60%. Bump that up if I'm doing 3D rendering or something. The math doesn't add up; the computer will have like 2GB of RAM being used and will say 80% usage or something asinine.
So I ran some tests on MemTest to make sure the RAM could fully be used in the first place, and it looks like it indeed can:

It looks more accurate now, with just over 6GB being used here, although the 92% still isn't entirely accurate.
Is this just a performance thing that Windows does automatically and uses RAM even when idle to keep it running, or should I be concerned here?
I've scavenged for any "ghost" memory hoggers and haven't found a single one (I've used process explorer among others...)
Thank you all for any help!

 

[rgd1101]

go to resource monitor to see where the memory is used

 

[Mechanics55]

go to resource monitor to see where the memory is used

I've done that as well. The usage still doesn't add up.

 

[Gfost73]

I had same issue with memory use going from 30% to like 80-90% when doing nothing on PC. I found a simple Registry fix that seemed to work on my machine,

open regedit run as admin ,

expand HKEY_LOCAL_MACHINE
\SYSTEM
\ControlSet001
\Services
\Ndu

in the NDU folder right click on START then modify, change the value of 2 to 4 then restart the PC. as well there is a service which can be disabled that may be causing the memory use however I did not disable this on my machine, but if you run "services.msc" as admin and search for "SysMain" which used to be named SuperFetch you can then right click on service, Stop service, then open properties and set service as disabled. I did not have to do this however, once I changed the registry key everything seems to be working great, my PC has been on for over 2 days now and memory hasn't hit over 60% usage yet, where as before it would be on a few hours and ive seen usage of over 90% just from watching videos online.