Need help pairing 2 memory kits / triple channel DDR3

Hello,

 

I've been using the same platform for about 5 years, a i7 920 on a Gigabyte EX58-Extreme with CMP6GX3M3A1600C8 Dominator DHX Pro 6GB.

Because i couldn't decide between a X99 and Skylake, i chose to add 6GB more to my old configuration.

I could not find the exact memory kit, so i bought CMX6GX3M3A1600C9.

 

The problem is that Win10 sees 12GB installed, but only 6GB usable.

BIOS and boot memory check only shows 6GB.

I had the original memory in slots 1-3-5, and the new ones i placed in slots 2-4-6. The other way around won't work, because the DHX Pro is really tall and slot 2 is "under" the fan of Noctua U12S.

Before i installed the new kit, i cleared the CMOS and let the settings unchanged.

From here on i don't really know what to do.

My guess is i should set the CL9 timings in BIOS?

Also do i need to raise the voltage of the QPI?

I've read some forums, but it's still unclear.

I need some guidance, a starting point.

 

PS: i use BIOS version F12, latest beta F13s won't boot with both kits installed.

 

Thanks alot

I have managed to fix the problem by swapping position for the memory sticks, meaning i put the better ones in the secondary slots, so the motherboard would read the slower timings from the XMS3 kit and adjust for the Dominator.