patros wrote:
4gb RAM? Hmm. Sounds fishy. You might want to check the RAM installed and see if they are OEM or after-market, put in maybe by the guys who sold it to you. I seriously doubt Asus would launch a G750 with JUST 4gb RAM on board.

That being said, DDR3 is only enabled when you have 3 RAM chips of the same make, type, speed and capacity installed in tandem. Which is why in my case, I got 3x8GB Hynix ram installed by Asus as part of the package.

If you do want to improve your RAM performance, in your case, you might want to either install 2 more 4 GB RAM modules after confirming whether or not you're using the right RAM in the first place at an ASUS tech center. They will verify the RAM you already have installed and then look at upgrading you.

3x4gb should suffice, however if you want more and want performance out of the DDR3 configuration, you might want to change them to 3x8gb. Remember, their voltage should be 1.35 v rating as opposed to the older 1.5 v rating.

Hope that helps!

the g750 cpu is only dual channel (and not triple channel as other corei 7) http://ark.intel.com/products/75116/

anyway asus choosing to put a single RAM module in the 2 internal slots will give poor performance due to single channel used - compared to dual channel the perfomance impact is between 2% and 20% acording to diffferent sources. (so asus, please use 2x2gb for the 4gb versions or give us easy access to the 2 internal slots without unscrewing the whole computer and voiding the warranty in order to get dual channel performances on the 2 first slots)

amanieux wrote:
the g750 cpu is only dual channel (and not triple channel as other corei 7) http://ark.intel.com/products/75116/

anyway asus choosing to put a single RAM module in the 2 internal slots will give poor performance due to single channel used - compared to dual channel the performance impact is between 2% and 20% according to different sources. (so asus, please use 2x2gb for the 4gb versions or give us easy access to the 2 internal slots without unscrewing the whole computer and voiding the warranty in order to get dual channel performances on the 2 first slots)

It is disappointing that the design requires the entire keyboard plate to be raised to get access to the memory. I was told by the Technical Inquiry people that the warranty would be in jeopardy by doing the memory replacement myself, and told to send it / take it to an Asus Approved Service Center. But, another support contact said it was ok to replace the memory as long as I didn't damage anything - and that the Asus Service Centers won't help with upgrades. What to believe?

First Technical Inquiry response:
"I attach a picture, you can refer to it, it seems there are 2 memory slots located there, and another 2 memory slots in its back side, which are located under the keyboard or motherboard, you can only change/upgrade the RAM card in the accessible back door by yourself, this dose not void your warranty. But if you want to upgrade the memory which is under the keyboard or motherboard, this process of upgrading need to disassemble the laptop, you should contact the local service center to help you do this, otherwise you will invalid your warranty. Thank you for understanding!"

Snippet of Live Chat from today:
...
Me Wed, 9/11/2013
...Apparently the 2 slots under the keyboard aren't user serviceable - we have to send in the laptop to put memory in those slots or we void the warranty...

Asus Wed, 9/11/2013
you will not be able to send it to us to have the memory upgraded as we doo not assist with upgrades Mr. Me. If you upgrade the memory the warranty is not voided if no damage is caused.

Me Wed, 9/11/2013
Can you send me an email confirming that? I had heard we can only go in through the bottom access panel and only reach 2 slots, the other 2 slots are under the keyboard and requires a lot of disassembly. I was told I needed to have it done by an Asus service center.
There used to be an Asus service center nearby in XXXXX, is that still operating?
what is the closest asus service center to me at zip code XXXXX?

Asus Wed, 9/11/2013
I will not be able to send an email to you with that information Mr. Me.
We do have a service center in XXXXX, but they will not be able to assist you with this issue.

Me Wed, 9/11/2013
My technical inquires say different... they say I can't open the area under the keyboard and to send it to an asus service center, you might want to update your info.
I can find and send you the responses.

Asus Wed, 9/11/2013
I do apologize Mr. Me, but we do not assist with upgrades.

Thanks for the info amanieux, I learned something today :). I was still stuck on the older i7s as that's what's on my desktop and I built that from bottom up. I also found out in my research that dual channel and triple channel are almost identical in performance too. Now what about quad channel in the Xeons? That just marketing or something worth looking into in my next desktop?