I just purchased an X79 mobo. Didn't think I needed 16gb so just went with the 8gb. Unfortunately, accidentally put 8gb 2x4gb in my shopping cart instead of the quad channel pack (4x2gb) . Instead of doing an RMA and paying the restocking fee, I'd rather just go down to best buy and pick up another 2x4gb.
My question is: should I just pick up more RAM or is it important to get a "complete set" that has been manufacture-tested to work together? I feel like this is kind of a gimmick, but I've also heard people say otherwise. Bottom line is I want to take advantage of the quad-channel performance.
RAM is Corsair vengeance DDR3 1600.
Mobo is ASUS P9X79 Pro
The memory controller on Intes current cpu's is very good, and is able to keep the cpu fed from any speed ram.
I think ou will see very little difference in dual channel operation vs. quad channel operation for most tasks.
Such benchmarks that are not synthetic, but represent real apps are hard to come by.
For some insight, you might read this on the effect of ram speed: http://www.anandtech.com/show/4503/sandy-bridge-memory-...
For your plan of buying a second kit, there could be some issues.
1. Ram is sold in kits for a reason.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards can be very sensitive to this.
That is why ram vendors will not support ram that is not bought in one kit.
Although, I think the problem has lessened with the newer Intel chipsets. Still,
it is safer to get what you need in one kit.
2. A motherboard needs to supply the same voltage to all ram. It is easier to do this with 2 sticks compared to 4.
If 8gb is really all you need, then I would just keep the kit you have.
If you want 16gb, go ahead and buy a duplicate 8gb kit. I think the odds are remote that you will have a problem, but no guarantees.