just a little info on one-sided and double-sided ram...
the double-sided ram has memory chips found on both sides of the ram...the computer looks for data one side at a time, thus, it cannot "see" all the data in your ram at one time...it needs to switch sides to look for data...the memory chips used in these types of ram are low density memory chips...
the one-sided ram on the other hand has all its memory chips on one side..the memory chips used on these types of ram are high density chips which can store twice the amount of data than low density chips thats why they are found only on one side... thus, "theoretically" it takes less time for the computer to look for data because it does not switch from one side to the other...it sees all the data in your ram at one time...
BUT in reality, you cant really see the difference in performance between the two(double-sided and one-sided)..or if there is any difference, it is minimal and unnoticeable...
when you opt for dual channel configuration, you should have similar rams(i.e. both should be double-sided or both should be one-sided)..your rams should also have the same timings, and same capacity...based on my experience, dual channel configuration cannot be used if one ram is one-sided and the other is double-sided...
hope this info helps....