are you saying that really i should run this in a m/b designed with 3 slots? or remove 1 chip and only run 2? or if i find a 4th chip would this solve the issue? i could buy another 3 pack then sell 2 chips as spare.
(Apologies in advance for the long answer!)
Most motherboards have the option to run RAM in "dual channel" which means they're making simultaneous requests to 2 RAM chips at a time, thus doubling your memory access rate. Expensive i7 boards have triple channel, thus... well, tripling it
In practise, there can be slight differences between memory chips of the same model, same way that CPUs, even from the same batch, can be different overclockers. When sold in double or triple packs, it's guaranteed not to have significant differences, and to work perfectly as a pair/trio (unless it's OCZ, in which case there's a good chance it's broken long before you open the box
)
With your motherboard, you can run 2x dual channels, which means it would optimally like a matched pair for channel A, and a matched pair for channel B. Your manual will tell you whether A means "both red slots" or "one black one red"
(You don't have to ensure all 4 are a perfect match, as long as the ones on the same channel are.)
Your current problem is twofold:
1) With 3 sticks in that motherboard, you can't run dual channel (because 3 does not divide by 2), so your memory throughput will be lower. In all fairness, the extra capacity is more than worth the loss of dual channel
if you max out 4GB regularly.
2) If you drop a 4th stick of 2GB in, then you'll have channel A operating a properly matched pair, and channel B operating a mismatched pair. It
might work. It also might not. I don't actually want to suggest either way, because sod's law says I'll chose the wrong option - just want you to know the possibility exists for it to go either way!
TLDR:
If you aren't happy with 6GB in single channel mode (which will be perfectly stable and usable - don't fix what ain't broke, etc!), then given how cheap you got the pack of 3, my thoughts would be to shelve 1 of those sticks, leaving 2 of them in memory channel A, and buy another 2x pack for channel B. They don't have to be the same brand, just the same speed/CAS ratings, which in this case is 1600MHz, 9-9-9-24.
Compatible products from OCUK:
G.Skill RipjawsX 2x2GB (I personally favour these because... well, I have some, and they're nice and solid.)
Corsair XMS3 2x2GB
Corsair Vengeance 2x2GB
You could also use a 2x4GB set (e.g.
these) and have 12GB total. I do this myself, works fine and happy and is a lovely large amount of RAM for a photoshopper
