Bios displays half of RAM - memory controller?

Question

Processors

Good afternoon!
I don’t know if I’m writing there, but for some reason, I remembered the toaster)
In general, there is a motherboard - ASUS P8H67
Processor - Intel Core i7-2600K Sandy Bridge
4 memory sticks 8GB each - DDR3 Corsair CMZ32GX3M4X1600C10
The problem is that the system, including BIOS does not see half of the memory.
Using the method of enumerating the bars, I concluded that all the workers, because leaving only 2 out of 4, everything works fine.
On the mother, two even slots do not want to see the memory.
I sinned on a stone - I got it, checked the legs on the socket, everything is fine. Cleaned, lubricated, installed - it works, but also half of the memory.
Previously, everything was fine, all 4 saw each other regularly. I did not pay attention, I do not know when and why it fell off.
What do you think, what is the problem, where to dig? Thank you! If not in the topic, I ask the moderators to remove the post.

Answer 1

try lowering the memory frequency.

Answer 2

The mother does not pull the frequency of the bars 1600
4 x DIMM, Max. 32GB, DDR3 1333/1066Hz Non-ECC, Un...

Answer 3

90%, which is the percentage (the memory controller is in it). Try to "deflate" it. I don't remember if it's possible to adjust BCLK and other frequencies in the BIOS on mothers with an H67 chip, but if possible, try lowering it. Although it is possible that there is a bug in the motherboard. Try resetting the bios.