Windows 10: Ram: Dual Channel & Volt

So I am thinking about buying a 8 GB RAM for my laptop. I have a few question about RAM regarding volts and dual channel.

#1
My current ram shows it is running at 1.5 V. Can I put it a 1.35 V ram instead?

#2
When I put the 2x4 RAM in my laptop, will it dectect that I am running dual channel or do I have to activate from the BIOS. Because my bios is very basic. It can only change boot and some other options. My manual shows it can support dual channel.

The ram I am buying this

$31
Mushkin Essentials 4GB DDR3 1333MHz CL9 SODIMM (991647)
Timing 9-9-9-24
1.5V
CL9

So the total would be $70.00

:)

 

Dual Channel and Flex mode

I would like to know how dual channel and flex mode works. I think I do but need some clarifications please.

I have 1x 4gb DDR3 and 1x 8gb DDR3 totally 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 ram 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 ram 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

 

Usable RAM

I have 12 GB of RAM installed however Windows say that only 8 is available (basically it doesn't see 1 RAM stick out of 2. Also when I place those 2 in dual channel everything is okay. But if I add more RAM to the non-dual channel
slot, this stick won't be usable (it is recognized, since windows properly says how much RAM I have installed) either.

I don't have limitation in msconfig and there doesn't seem to be anything related to the problem in BIOS (MoBo GA-970-DS3P). I also don't have integrated GPU.