Question Asus Sabertooth 990fx r2.0 memory

[anedic]

I have old Asus Sabertooth 990fx r2.0 motherboard with AMD 9590 CPU and installed 32 GB Kingston HyperX Furry DDR3 1866 memory (4 sticks with 8GB memory). Bios is latest.
Mobo boots OK, but I am interesting why Bios is showing 32752 MB instead of 32768 which is 32GB. Where is 16 MB missing? All 4 sticks are recognized correctly in EZ profile.
Windows 10 shows 31.9 GB max memory (0.1 GB reserved).

 

[Lutfij]

Welcome to the forums, newcomer!

People always say BIOS is latest until they come to the point that there was a BIOS version pending update. So if you will, please mention the BIOS version. Since you're on Windows 10, what version(not edition) of the OS are you on?

 

[anedic]

Bios is 2901 version, Windows 10 21H2

 

[anedic]

I made a little experiment yesterday. I remove all Ram sticks (it is two pairs of 8 GB paired memory), and put:

1. Kingston 4 GB Ram DDR3 stick in every slot, and all four times it shown 4096 MB Ram total.
2. One 8 GB stick in every slot, and it shown 8192 GB total memory. I just do the same for other 3 sticks in all slots and shown exactly the same (8192 MB).
3. One pair sticks in two slots (one channel) and shown 16384 MB which is OK. I change the channel and get the same result.
4. Same experiment with other pair of sticks and get the same result (16384 MB).
5. All sticks in four slot and get 32752 MB Ram.

So, memory sticks are OK (I tested it before with memtest86), but when all slots are populated there is loss of 16 MB Ram.
I thinks that AMD series of FX processors are having trouble when all slots are populated, specifically it memory controller unit which is 128 bit.
What do you think?
Does AMD Raisen have the same problem when populated all memory?