Can I use 3 slots with dual channel ram?

[Get_off_my_plane]

I'm using Crucial Ballistix Sport DDR3 1600 type ram; I currently have two 4gb modules installed.

Can I safely add another 4gb into one slot, using up 3 slots, or must I divide that 4 into 2gb modules and use all 4 slots? Is anything lost by doing this?

 

[WyomingKnott]

What you would lose is that your ram would run as single-channel, which would give you slower overall memory performance. Whether the RAM runs as dual-channel or not is up to the motherboard and you must populate the correct slots; if you put two sticks into two slots for the same channel then you will get single-channel performance anyway.

 

[Tradesman1]

Depends on the mobo - if an Intel mobo or fairly recent AMD mobo adding a third stick would result in a split - 8GB running in dual channel and the odd 3 rd stick running in single channel. Intel mobos use their flex mode to manage DRAM and most recent AMD mobos mimic flex mode on their mobos. The big thing will be is all the sticks will play together at all. It's not a good idea to mix sticks/sets of DRAM