Okay, but it is triple channel motherboard and performs best with sets of three identical memory sticks (so 3x4GB) -- very odd that it has 4x1GB. And that was a good price for all that gear.
I would just use the 2x4GB kit. If the timings, speed, and voltage are identical you might get by with the other sticks in, but unless you have a real need for 12GB it is probably not worth the hassle.
And what motherboard do you have that has 6 slots and only had 4x1GB installed before?
It's an MSI x58 LGA 1366 mobo. I dont know exact specs. I bought the mobo with an i7-920, 4gb ram, 120gb ssd, 500gb hdd, hd 5750, and a case, all for $50 so i did some upgrades
Okay, but it is triple channel motherboard and performs best with sets of three identical memory sticks (so 3x4GB) -- very odd that it has 4x1GB. And that was a good price for all that gear.