An other question that we can have is “brand chip or noname ? “. This depends on the tastes and the budget, but for the memory i will advice brand chips. The performances are in general really good and the chip is often guaranteed for a long times (sometimes for all the life). In the big constructors of chips we can include Corsair, Kingston or Crucial. You will rarely have problems with chips of these brands.
Normally the memory chips doesn’t need to be specially freezed, but on the big configurations very used, it’s useful to freeze the chips. The best way is to use a simple heatsink (a lot of chips are directly selled with heatskins. There is also other systems like liquid cooling of fan system. But i’ve never seen a case where the heatsink isn’t enough.
So the first thing to think about is the necessary quantity of memory. Once this is done, you have to see with your mainboard which chips you can use and make the good choice considering the budget and the need of performances.
I hope that this article will be useful for the choice of memory chips.