Dual Channel and Flex mode

[cespencer]

I would like to know how dual channel and flex mode works. I think I know but need some clarifications please.
I have 1x 4gb DDR3 and 1x 8gb DDR3 totalling 12gb. So, CPUID says they are running in dual channel mode.
My questions are as following:
Q1) 1x 4gb + 0.5x 8gb are running in dual channel; and remaining 4gb is running in flex mode. Is that correct?
Q2) If I consume over 8gb of memory then what happens?
a) 4+4 gb will be running in dual channel, and remaining 4gb running in single channel mode? Or,
b) the entire 12gb will be running in single channel mode?
Q3. Any difference whether I place my modules back or front? For example, 8gb in slot 1 and 4gb in slot 2; or reverse 4gb in front and 8gb in slot 2?
Thanks

 

[Lutfij]

2| Your system sees 12GB of ram. If the system needs more than that, if on Microsoft's Windows OS environment, there will be a warning message asking you to close your other apps.
1| You didn't state the make and model of your motherboard. On second thought's you would be best served passing on your full system's specs and you OS.

Since you've got more than 4GB of ram, you should be on a 64 bit architecture of Microsoft's OS platform(or any other for that matter). This thread could help shine some light on the Flex/Dual channel thing.

 

[k1114]

1) Flex is not a number of channels. All 12gb is in flex mode which really just means you are running dual+single. As you said. "4+4 gb will be running in dual channel, and remaining 4gb running in single channel mode"

2) The number of channels don't change, you are still running in flex mode. When you go over 8gb you'd then be accessing the other 4gb in single. You'd have a lower ram bandwidth but for most uses, it makes no difference.

3) No, you are still running in the same config for flex mode.

 

[cespencer]

Thanks so much for your reply. I have been reading about and wasn't sure if that was the case but you have clarified that for me.
I have an AIO with 2x4gb and a laptop with 2x8gb. As I hardly use more than 4gb I found the additional ram on the laptop wasted. So I decided to split them and now have 4gb+8gb on both AIO and laptop. Therefore, I still have 4gb+4gb in dual channel and if it ever goes over 8gb I still have another 4gb spare. Awesome. Thanks again.