PDA

View Full Version : DDR-4, Dual Channel vs. Quad Channel



BrotherDragon
21-07-2015, 06:49 AM
I'm researching components for a new computer I'm planning in September when Intel's Skylake processors come out. I want to start with 16gb of DDR-4 2133 RAM but I don't know if I should go with 4x4 or 2x8. If I go 2x8 I can easily expand to 32gb later. If I go 4x4 my memory will be operating in quad channel whatever that means. So I guess what I'm asking is what is quad channel and does it provide a significant performance boost?
______________________________
"I'm trying to think but nothin' happens" -Jerome "Curly" Howard

dugimodo
21-07-2015, 07:53 AM
Depends what you use it for, quad channel has more bandwidth and is a little faster but in day to day computing and games you will never notice the difference. If you run memory intensive applications it may be worthwhile. Give us some more detail and maybe we can tell you if it'll matter.

BBCmicro
21-07-2015, 08:51 AM
I'm planning on doing almost exactly the same as you (Sept, Skylake, 16GB etc)

In my case I want a mini-ITX MB (probably GA-Z170N-Wifi) and they only come with 2 slots

dugimodo
21-07-2015, 09:28 AM
A bit more info. Up until now Intels mainstream CPUs only do dual channel and the high end enterprise class (haswell-E etc) do quad channel. As far as I know Skylake is adding DDR4 but is still Dual channel in the mainstream range. Skylake-E is still a fair way off as planned and I doubt you'll be doing that in sept. so basically 2 or 4 chips will still run in dual channel mode.

Another note, although it is possible to add RAM later and it "Should" work there are no guarantees. The reason RAM is sold in dual and quad channel kits is to ensure the Chips will work together and often adding more later can result in stability issues or require a bit of advanced tweaking of timings and voltages to make it work. Even the same brand and model RAM can have this issue.

Basically it's best to start out with as much RAM as you are likely to want in the life of the PC, and if you do upgrade later it's better to replace your old 16GB of RAM with a new set of 32GB and sell the old RAM. Buying a 2nd set of 16GB and adding it is rolling the dice to a degree, it'll likely work but you may end up with 2 sets of RAM that will not work with each other.

BrotherDragon
22-07-2015, 05:03 AM
Thanks for the feedback. I've personally never had problems with starting with two memory slots and adding the other two later so I probably go with the 2x8gb solution. I use my computer for general use and to play games(99% Dragon Age: Inquisition) and am always under significant budget limitations otherwise I'd just get 32gb of RAM to start with.
______________________________
"I'm trying to think but nothin' happens" -Jerome "Curly" Howard

dugimodo
22-07-2015, 07:36 AM
That being the case 16GB is plenty and you may never need to upgrade it. I still run 8GB and have for several years and have yet to have a memory issue. My next build will have 16GB but only because I think it's worth it in case I need it in future not because I think I need it now.

BBCmicro
22-07-2015, 08:27 AM
I often use all my (8 GB) memory. The screenshot is after queuing various jobs in Adobe Premiere Pro CS6 then hitting Go in Adobe Media Encoder

dugimodo
22-07-2015, 08:46 AM
That is high memory usage but not many people do that. Also there is still 1.4GB available in that screenshot so not too bad in that case.
Windows will typically use all available RAM for caching and the like and only release it as needed so you will not normally see much free memory in resource monitor regardless of how much RAM you have. The green bar is the important one and you are using most of your ram in that shot.

I'll have a look tonight but typically for me even when gaming and running something on the 2nd screen I seldom exceed 50-60% of my 8GB in use. Any 32bit application (and that's till a large % of them and most games) can only use 2GB under normal circumstances.

As having 8-16GB becomes the norm though programmers will start taking more advantage of it.

Agent_24
31-07-2015, 01:07 PM
I run 8GB now, would consider 16GB next build too.

16GB should be plenty for you, and if you can get it faster in Quad Channel, why not? I can't imagine why you'd need 32GB if all you do is general use and gaming.