CORSAIR Vengeance 2x4GB bundle vs 1x4GB 2pcs

Supahos

Expert
Ambassador
Its best to buy it together in a kit all at once, as soon as you start mixing memory results can't be guaranteed. Usually a few voltage tweaks in the bios can sort things out, but just know there is always a chance whatever you buy will not work with the first stick you buy, even if it is the exact same model.
 

Tradesman1

Legenda in Aeternum
And oft times you don't, but often you do, which is why it's best to buy a single set, that way they are tested to work together and at advertised freq, also XMP (if 1600 and up) is programmed by the set and number of sticks...Have seen many mix and say there's no problems and then the people take a look and find they have bought and paid for good 1866 or whatever DRAM and yes it's running, though often at 1333 or a lower freq and loose timings, so big drop performance wise from what was paid for and expected....just one of the many reasons that DRAM is misunderstood