That can be true also, but then too for most anybody, I'd rather have too much then have something come up and find I have too little. And here if OP simply tries to 'add' a 4GB stick to get to 8GB, there's no guarantee it will play with the old, but by getting the 2x4GB, OP knows they have a good 8GB and if the 4 plays it's sort of a freebie bonus, if not no great loss, still have 8GB. If 8 is needed and an additional 4GB wouldn't play then it might be a couple of weeks to return and get new new sticks (plus may have to pay restocking fees, or the place might have a no return policy - then be stuck with two 4GB sticks that won't play..........