2 sets of CMD32GX4M4A2666C15 on ASUS rampage V

Dear all,



I recently assembled a computer with ASUS rampage V mainboard.



I got two sets of

CMD32GX4M4A2666C15



totally 64GB.



However putting them all will make the system unstable --- freeze every few minutes --- unable to use at all.



So I only use 32GB and it works great.



Could I know if there is a way to use all 64GB? Like adjusting somewhere in the BIOS or anything. The other 32GB are just sitting there is a waste....



Thank you for any hint!



Best,

yi