What's better: dual-channel memory mode or a bit more RAM?

[Adam Funk]

On 2011-05-01, Jordon Bedwell wrote:

> On 5/1/2011 3:25 AM, Adam Funk wrote:
>> On 2011-04-30, NoOp wrote:
>>> That is to be expected; the system will always default to the lowest
>>> speed memory (otherwise the slower chip(s) won't work).
>> That makes sense; thanks.
>
> Wait, I thought they were the same chips?

DDR1 & DDR2 are identical to each other; 
DDR3 & DDR4 are identical to each other; 
but 1 & 2 are not identical to 3 & 4.