Hi, Thank you for the information. I did populated both black slots with 4Gb rams each,nothing in the white slots, I presume this population is correct, but it did not, now I tried the rams individually in first black slot, they started to get error message 201, where initially they did not get this error message when I tried them individually,therefore they must have changed when I populate them together in the dual channel mode.
The map in the manual may be bit confusing,but it is simple we have 4 slots,two blacks,two whites,the black ones are one to the outside and one in the middle so is slot 3, and the white slots one between the two black slots so is slot 2 and one to the outside so is slot 4.
I have checked the BIOS and it shows rams are installed in dual channel mode as PC still can boot after this error message 201.
Now I can make the pc runs ok without error message by populating 2 Gb ram in slot 1, and 2 GB ram in slot 2 (White) and 4Gb Ram in slot 3 (Black) the 2GB rams are DDR3 1333 and the 4GB Ram is DDR3 1600.
I appreciate your further help.
Thank you for the support.