Quote Originally Posted by tuberculo View Post
Thanks for all the replies.
I have already tried memtest, but I did not run it for a long time, I'll try that later.
If I want, I always manage to have 6 GB of RAM, but I have to reboot a few times. That's annoying. I think the problem may be in Ubuntu because, in BIOS, all the memory is recognized every time. The command lshw also recognizes 6 GB.
My motherboard is A55M-HVS. There are only two banks. I have already switched positions, with no result. I also tried BIOS update.
I will try Lightning Dragon's idea later.
Did I understand this correctly: The command lshw also recognizes 6 GB always?

Then I am surprised that free will not show it. I suggest that you try Lightning Dragon's idea to change places of the RAM cards, and consult the manual to your motherboard like Joao Lacerda suggested.