Originally Posted by liberalelephant
I would go on the OCZ forum and ask someone in-the-know if those RAM sticks use the same IC's as the 4GB kit. You will probably be fine but if I were you I would make sure.
Good advice and I'd follow up on it.
The IC's have to be the same or your RAM is mismatched. Mismatched RAM can cause some real problems such as random crashes, lockups and in some cases cause your machine to not boot at all. Also if using sticks from different sets, make sure the version # of that model is the same - Corsair for example has sticks with the same exact model designation but the version is different meaning the IC's are different.
As an example with these, I have two sets of Corsair XMS CMX256A-3200LLPT XMS3205 sticks, purchased new at the same time from the same vendor (Newegg) and the only difference between these two is what's immediately after the XMS3205. One set is stated as being v1.1 and the other is v1.2.
The 1.1's are BH-5 sticks and the other set are CH-5 sticks.
These sticks as I've already found out for myself don't play well together and actually conflict with each other inspite of having the same timing specs and voltages specified for them.