Guys, i'm since lowyat's selling only a pair or twin for High Performance RAM, i'm wondering

1. Can RAM run together with the different clock value or even totally different brand.
- if no, why, and why is it not good.


2. Issit it must run in pair, or it's only a strategy to force you to buy two.

3. If there is, where else in Selangore can I buy High Performance RAM instead of Lowyat, which sells single ram, not pair. cuz i only need one to upgrade.


No childish answer pls. serious and constructive.