dual channel does matter?

[KellerKind]

ok here is my question, is any difference between 2x4 gb ram memory and 1x8 gb ?

 

[chrisso]

2x4 will run in dual channel mode.
Dual channel set ups will run 'bank interleave',meaning the ram controller can overlap how it talks to the memory. Typical performance increases of the whole system in games for example, are around 8 % perhaps more with new systems. A single 8 gig stick is only an option if you already have one doing nothing,
or are planning on buying more later. Please note well; adding ram later can be problematic even with same brand and model sticks,if you are unlucky.
Big ram setups (2x8,say) should be bought as matched pair kits to avoid any problems.
2 X 4 is more than enough for games and general use.