my questions are: 1) is is possible to install a RAM like this:
DIMM_A1(blue) populated
DIMM_A2(black) populated
DIMM_B1(blue) ------
DIMM_B2(black) -----
but the two RAM is not Identical..

2)how about this one:
DIMM_A1(blue) populated
DIMM_A2(black) populated
DIMM_B1(blue) populated
DIMM_B2(black) -----
the RAM at the blue socket is identical, but the one in the black socket is a different type and size.

just don't want to waste the availability of my RAMs ^^,
tnx in advance..

I know 2 will work but I do not know about 1 - it might be dependent on the MoBo

It depend on the hardware combination, Moreover, The Ram combination may be made according to the specification.

Hello,

You'd be better off checking the motherboard spec.

Post your spec here if you want us to check. some motherboards will require memory modules to be set up in pairs.

Post the spec of your ram aswell.

If the RAM is different, they will both/all run at the speed of the slowest card.