Question I have 16gb installed 8gb reserved by PC

[Zagirons]

I've came across a problem recently from my 16gb of ram only 8 is usable.
I have seen so many articles and everything but no help at all. I tried to change the cpu and everything worked 16gb was working fine, but as soon as i add the old cpu 8 gets reserved by system.
My PC R5 2600/ RX570/ 16gb 3000mhz/ ASROCK B350m-hdv/
Everything used perfectly before im really lost at this point no idea what to do.

 

[PrinceTexasLoaf]

I'm not entirely sure maybe try reinstalling the ram or if it's overclocked try removing your oc and put it to stock I once had ram overclocked or something like that years ago and it resulted in something similar.