If the RAM modules are not the same size, the system either will default to single-channel mode, will only run the amount of RAM on the smaller stick in dual channel, or will not work at all, depending on the motherboard and the memory architecture. In fact, I like using all identical sticks of RAM in any computer I build to prevent problems with subtle timing differences.Įach bank of RAM must have the same size and speed of RAM in both slots in a dual-channel configuration. In addition, although it is not technically required, I recommend that the two banks also be identical (same speed, same size, same manufacturer, same model).

The RAM sticks in each bank must be the same size.

The black slots would be one bank, and the blue slots would be the other bank. So you may have, for example, four slots, two of which are black and two of which are blue. The banks are usually identified by different color slots. In other words, a motherboard that supports dual-channel DDR will usually have two (or more) RAM banks, each of which will have two slots. Usually the slots of each bank are of the same color, but read your motherboard manual to make sure. If you are using DDR memory in dual-channel configuration, however, then you must fill the two slots of each RAM bank that you're using with identical sets of RAM. But a few motherboards require that you start with the first slot and fill them in order, so you may as well do it that way. If you are using SDRAM or single-channel DDR-SDRAM, then it usually doesn't matter which modules go into which slots.

Which ram slot to use