Actually, as it stands now, you are not running in "dual channel" mode. Normally, the color indicates each channel. In your case yellow being one channel and blue the other. In order to run in dual channel mode you therefore need to have one stick in the blue and one in the yellow or, 2 in the yellow and two in the blue. They should in theory be "matched pairs" or at the very least very close in specs (timings etc).
You can take the Samsung and install them into the remaining two slots and effectively give yourself a "dual channel" setup. Normally it is suggested that all the sticks be of comparable specs although size isn't important. As long as the specs from your OCZ and Samsung are close, you should have no troubles at all.
Again, each channel (same colored slots) need to have matched pairs, Installing a matched pair into one color only while leaving the other color empty will yield "single channel" results. Downloading and running "Everest" will show the differing results between them.
One further note: OCZ uses select Samsung ram, re-labeling it if passes their specs. I use OCZ myself.
