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ST9752
09-01-2017, 11:40 PM
I just expanded my G752VL from the initial 12G to 24G of RAM. My question is this. The original config is a single 8G stick and a single 4G stick located in the slots under the keyboard. The initial layout according to CPU-Z is

Slot 1 - Hyundai 4G DDR4 2400
Slot 3 - Samsung 8G DDR4 2132

I have added two more SODIMM's in the following configuration.

Slot 2 - Hyundai 4G DDR4 2400
Slot 4 - Patriot 8G DDR4 2400

Of course, on the first boot after changing the memory layout the 752 takes a while to POST (ram test maybe) and also to probably rewrite the hibernation file. After that it boots and acts normally.

My question is... Is the above layout optimal for the dual channel controller? I assumed that one of the slots below the keyboard was on Channel A and one was Channel B. Thus the matching slots would be accessible from underneath. That may have been a wrong assumption. What's the best layout for using 2 4G sticks and 2 8G sticks?

Thanks,

Scott

ST9752
09-02-2017, 02:27 PM
Am I just totally off base here? Memory controllers in the past required matching memory sticks for best performance. I assumed the same with the G752VL. Does it make any difference?

Clintlgm
09-02-2017, 03:53 PM
Yes it does, you'll have to match the timings and voltages, the 4 gb should be paired and 8 GB should be paired., Since your set up came from the Vendor screwed up, your stuck with what you got unless your willing to open the notebook and get rid of the 4 GB under there. I would get rid of it all while you have it open and drop in 2 16GB, leaving your two exposed slots open to upgrade in the future.
The lay out under the Key board is 0 -2, above 1 - 3, bottom ones are paired and upper ones are paired if you load Hwinfo64 you see this.
So I'm not sure how that works out having an 8 and 4 matched up, I suspect that only 4 gb would run dual channel maybe they won't run in dual channel at all since they aren't matched up. I would make sure that 0-2 are exact matches as well as 1-3 are exact matches, all four exact matches should make you error free. But the 2 in dual channel need to be matched up

ST9752
09-02-2017, 06:17 PM
Clint,

Thanks for the info. I ran HWinfo64 and it showed the normal slot numbers from 0-3. However it still didn't make it clear which slots are paired on a single memory controller channel. It shows:

Row 0 - Hynix 4G
Row 1 - Hynix 4G
Row 2 - Samsung 8G
Row 3 - Patriot 8G

It indicates the controller is running in Dual Channel mode.

Are you sure that the controller paired slots are 0&2 and 1&3? I still can't find that information anywhere. It would make sense to pair the 2 sockets under the keyboard and the 2 in the user access bay. Too bad ASUS didn't just ship it with matching sticks then this wouldn't be a problem at all. :-)

BTW, timings and voltages are all pretty well matched for these sticks. I just want to get the best performance out of them. If I have to crack the thing open, that's no big deal but I don't want to do that until I know for sure it will actually increase performance.

ST9752
09-02-2017, 06:38 PM
I found a link to the details of the Skylake H architecture and chipset features. The DRAM controller is all implemented on the CPU as expected.

https://www.intel.com/content/www/us/en/processors/core/6th-gen-core-family-mobile-h-processor-lines-datasheet-vol-1.html

Page 22 describes how the controller handles single and dual channel modes. It also makes it clear that Channel A should be the larger of the two channels in order to properly use the Intel Flex mode for dual channel memory access. So, unless you simply fill all four SODIMM slots with the same memory it's important to know if Asus attached slots 0 and 2 to channel A or channel B. Does anybody really know how they laid this out on the board? They could have done either.

Darnassus
09-02-2017, 08:07 PM
I believe that yap your RAM layout is wrong. Service Bay is paired, and the underside of your board (inverted) is paired.

If you want dual-channel you'll need to remove the internal 4gb and replace it with the 8.

Although... the performance wouldn't be bottlenecked at your ram, so you won't feel any difference other than the satisfaction of proper layout.

ST9752
09-02-2017, 09:58 PM
The impact, as you note, is probably not a major hit in real world performance. I wonder if some memory benchmark will show the difference? I may crack it open and reorganize the memory at some point but it's a bit of a pain and probably not worth it until I upgrade to even more ram.

Oddly though, both CPU-Z and HWInfo show the controller operating in dual channel mode.

Intel's flex memory tech is pretty good at adapting and creating as much dual-channel space as possible. The doc link above gives some clue as to how the controller might be mapping the mounted ram sticks. It could be that right now I'm only getting actual dual-channel performance from the lower 4G of each SODIMM resulting in 16G of dual channel and 8 of single channel. The controller has a rather flexible ability to map hardware memory into an optimal configuration as you can see on page 23 of Skylake doc linked above.

Darnassus
09-03-2017, 04:11 AM
I wanted to ask if the G752's actually quad-channel compatible a while back.. ;x

ST9752
09-03-2017, 12:21 PM
Don't think so. :-)

Clintlgm
09-03-2017, 06:17 PM
Mine is stock as it came from vendor. It is only running Dual Channel
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