This is what i did: i've removed 1 stick, so i had 2 sticks in dual mode, the reading was 400Mhz, removed an other stick, so only had 1 stick, reading was 400 again.
Then I removed 2 of my fathers sticks and replaced it with my memory, with his ram in my computer, i had a correct reading.
Then I put my RAM in his computer, he has a correct reading too. But when i put my ram in my computer, i goes to 400 again
I was stupid not to test the game 'HoN' to see cash loading difference but i will do this wednesday since I have no time tomorrow.