RAM halved after H100i installation

[Riccardo Bestetti]

Hello.
I've recently installed a H100i cooling system in my computer.
I've got a ASUS Sabertooth P67 motherboard with a i7-2600k and 4*4GB modules of Corsair Vengeance DDR3 RAM which had always ran at 1600MHz with XMP.
After the installation of the cooler, the MOBO still reports all the 4 modules in its interface, but the processor reports only 8GB of RAM, as every OS I've tested. Also, they now run at 1333MHz.
So, it looks like the modules themselves are fine, they work in any possible combination of 2 and I've memtested all of them so they all work. But when I insert all four, two of them just sit there doing nothing.
What could it be?

 

[photonboy]

My guess is the memory isn't fully inserted. Either that, or the motherboard is defective.

Your memory got reset, so change it back such as clicking "XMP" than saving that BIOS setting.

Also, run MEMTEST to not only test the memory but see if it's testing 16GB or 8GB (probably in MB which is 1024x more)

 

[Riccardo Bestetti]

My guess is the memory isn't fully inserted. Either that, or the motherboard is defective.

Your memory got reset, so change it back such as clicking "XMP" than saving that BIOS setting.

Also, run MEMTEST to not only test the memory but see if it's testing 16GB or 8GB (probably in MB which is 1024x more)

Sorry, I forgot to mention that with XMP the computer just refuses to start and I have to reset the motherboard.
MEMTEST is testing 8GB.

 

[Riccardo Bestetti]

I know I shouldn't bump topics, but I think that opening a new one with the same question is worse...