ram problem 7.93 is usable when i have 16

I Alredy have tried everything but no difference im planing to get one 16 gb stick , after that im not going to buy astock mobo bcs many have same problem like me so ty anyways

Again, you should be using A2 and B2 slots.

Beyond that,
https://superuser.com/questions/1514018/why-is-my-usable-ram-only-half-of-my-installed-ram

So it's apparently possible that one of the sticks is bad.
It is physically detected, but Windows can apparently find it to be faulty and excluding it from use.

Take the DIMMs out and clean the contact surfaces with alcohol. Carefully vacuum the sockets to make sure they aren't clogged with dust, etc.

Reseat them on A2 and B2 slots.

If no avail, try one stick at a time, in B2 slot. If one of the DIMMs is bad, it should become obvious.

What memory slots are you using?
One DIMM should be in the slot furthest away from the CPU socket.
The other DIMM should skip one slot.

CPU--empty,DIMM,empty,DIMM