You said you "can't" use the triple channel kit. But of course you can, so how is that useless? I am correcting what you said because it's misleading. A triple channel kit will work in a dual-channel motherboard, but not in its advertised triple-channel mode.
If you said it like saint19 did ("The i5 doesn't support tri-channel"), then it would have been correct.
IMO, don't have any sense spend money in a tri-channel kit, for run it at dual-channel mode. If you want 6GB, buy 2x2GB to run in dual-channel and add another 2x1GB for run it in dual-channel too.