Question 12GB goes to 8GB when all sticks are inserted

[lukejongibson]

I've got an Asus P6TD Deluxe MB with triple channel DDR3 and 6 sticks of 2GB ram, running Windows 10 64bit I've checked all the sticks work individually, and all the ports work separately, this set up used to run perfectly, but now when all the sticks are inserted it only shows 8GB available, If I remove one of the sticks it goes back up to 10GB.

As I said all the sticks work and all the ports work I tried all combinations, only when all sticks are inserted does the problem happen.

Does anyone have any idea what might be going wrong?

 

[helpstar]

does it show the wrong size in the BIOS or in windows

update/reflash the BIOS with ASUS EZ FLASH 2 on an USB flash drive
https://www.asus.com/Motherboards/P6TD_Deluxe/HelpDesk_BIOS/

reset the BIOS by jumper (clrRTC) while power is off and all sticks are tightly connected to the slots.

 

[lukejongibson]

does it show the wrong size in the BIOS or in windows

update/reflash the BIOS with ASUS EZ FLASH 2 on an USB flash drive
https://www.asus.com/Motherboards/P6TD_Deluxe/HelpDesk_BIOS/

reset the BIOS by jumper (clrRTC) while power is off and all sticks are tightly connected to the slots.

Both Windows and Bios