Question Memory issues

[Nadav6565]

I need help!
My computer is having memory issues.
I have two sticks of ddr3 8gb ram and my computer only registers 8. I’ve ran memtest and windows diagnostic tool And both show no error.
My computer has this little freezes and I get blue screens.
How do I know if the problem is the motherboard or the ram itself?

 

[rgd1101]

full system spec? need exact model

 

[Nadav6565]

Mb is asrock h81m-HDS
Drr3 8gb 1600mhz
Intel i7 4790
Gtx 960

 

[Nadav6565]

Computer will only boot with both ram sticks