single vs dual channel

Recently built a new system after being away from PC's for a while and my research only went as far as finding out that 8GB of RAM was "enough" for gaming and browsing, so I just grabbed a single stick of 8GB 2400mhz DDR4 (Corsair Vengeance LPX).

I've just been reading about dual channel RAM, and I'm not sure if I made a mistake buying a single stick of 8GB, or if I should have bought 2x 4 GB instead to make use of dual channel?

My intention was to buy 8GB now, and another 8GB in the future when needed. And I thought 2400mhz was fine, but it seems a lot of people use atleast 2666-2800 mhz, although some say it makes no difference.

So if/when I eventually upgrade to 16GB, should I swap out the single 8GB for 4x4GB and maybe higher speed, or just throw in another stick of 8GB 2400mhz?

And what if for some odd reason I added a single 4GB to go with the 8GB that's already in there, how would that work in the case of dual channel, does dual channel work with different sized memory or would you have to place them both on the same channel?

What's the rest of your system?

MHz speeds with RAM don't make a huge difference (a little more with DDR4 than 3) unless you are running a stupidly high end system or using an integrated graphics solution you probably won't see much if any difference between 24800MHz and 2800MHz.

I always recommend going dual channel (or quad) where appropriate - the CPU has been designed to work optimally with a certain configuration and while many things work fine with slower RAM configurations you may find some areas it struggles which might manifest as stuttering, etc.

i5-6500, XFX R9 390, Gigabyte Z170 Gaming K3

Another question along with the OP, I've just been checking RAM prices and the stick I bought has gone up by £10+ is it normal for prices to fluctuate like this? It was only about 2 months ago I bought it.

ste91 said:

I've just been reading about dual channel RAM, and I'm not sure if I made a mistake buying a single stick of 8GB, or if I should have bought 2x 4 GB instead to make use of dual channel?

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Honestly the difference between single and dual channel is overrated most of the time. Outside of synthetic benchmarks e.g. stuff like Sisoft Sandra or Everest's Memory benchmarks, the "real world" difference in most games etc is somewhere around the 5%-10% mark.

ste91 said:

Another question along with the OP, I've just been checking RAM prices and the stick I bought has gone up by £10+ is it normal for prices to fluctuate like this? It was only about 2 months ago I bought it.

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RAM has one of the most volatile pricing around, it's a combination of factors but largely it's quite time sensitive (e.g. the actual chip manufacturers - not necessarily the same manufacturers who build "sticks" of RAM) have to guess the demand e.g. as to when to stop production of one memory technology e.g. DDR3 to move to DDR4.

Guess correctly and there is enough RAM for demand, so prices are fairly reasonable, guess wrong and start too late and there is no inventory so prices are inflated. Guess wrong the other way, and there is literally so much RAM "in the channel" that it has to be sold too cheaply to clear inventory.

I think ram is imported so subject to sterling varying quite a lot recently, might be some of it

Minstadave said:

What's the rest of your system?

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How about threads or cores in a system. I saw a new Intel chip with 22 cores in 1 cpu so 44 threads. Is this where quad channel is going to show up as vital.

If a benchmark fits all into the onboard cache then it wont matter, with some the cache is 30 meg or more. But a wider test or real app using over 10 threads would appreciate 4 or even 8 sticks available to all those threads I wonder, anyone found that at all ?
I know a lot of software is 4 threads if that but say that guy running a lot of VM, would he see a large gap in performance if going dual channel or would speed change from 2400 to 3000 show more with multiple cores also.
If I see a chart for this test I'll edit it in

I would buy a matching 8GB stick now while you still can, you may find in 2 or 3 years when you decide to get the second stick that it isn't available any more.

From memory (no pun intended), dual channel gives you a roughly 5-10% performance increase.


edit, looking at this, it's more like 0-~20%.

http://www.gamersnexus.net/guides/1349-ram-how-dual-channel-works-vs-single-channel/Page-3