Is Dual Channel Worth It? Will I Notice?
Dual Channel is a neato way of improving performance but that's really only for instances where it's really needed (see definition of Dual Channel). An easy example of where dual channel will give
zero benifit is if the memory operations are exclusively within one of the channels (i.e., for small stuff). Even when you do stuff that dual channel has a benifit, the most you'll see is like 10% (less for AMD-Socket754 processors since they have an on-die memory controller which gives it the majority of it's gaming performance).
To avoid misinterpretation, what i mean is that "comparing a Dual Channel system to a Single Channel system will result in a performance delta of no more than 10% -- even less if we specifically choose a Socket754 processor since the impact of having an ondie memory controller is much more significant than the lack of dual channel"
Dual Channel Kit... What's That?
Memory manufacturers, jumping on the dual-channel buzzword are releasing ... "two sticks of memory in one box". That's essentially what Dual Channel kits are: when building a dual channel system, to use dual channel you'll have to have two (or four) sticks of memory so buying kits with two sticks of memory will save the number of boxes you'll have to open. Of course according to the manufacurers they say they test the two sticks together on a motherboard to see if they overclock and run stable (nothing about being able to run faster than if you bought two sticks separately yourself).
Unless you've got a lot of money to blow and want that "extra assurance", you're best off buying two sticks on their own: as long as they are the same specs you can dual channel it up
What Do I Need to Run Dual Channel?- A dual channel capable motherboard/CPU
- Two or four sticks of identically spec'd memory (they dont need to be the same brand and make although that helps but they need to have the same clock and timings or be capable of the same clock and timings)
- See motherboard manual for how to install it but generally speaking the slots will be color coded: fill one color first before moving to the next
Can I Mix Between Memory Speeds?
There are some motherboards that are really finicky with their memory however in general if you mix two (compatible) memory modules (or more) they will all run at the speed of the slowest module so you'll be ok. This also applies to installing higher speed memory than the slot is rated for. Another option of course, is to overclock the modules so that, in effect, you force the slower module to run at the same speed as the faster module
DDR or DDR2?
If you're running a board where this is an option, the budget and bang-for-buck option is probably to go with DDR as the high performance DDR2 stuff is quite expensive. The gist of it is
DDR2 features higher clocks but also at significantly increased latencies (with the exception of the really pricey stuff There are some good reviews to read about the progression of DDR2 vs DDR: