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aprilia1k
12-27-2014, 01:37 AM
I've been reading that mixing SODIMM's of different make and/or specs is "hit or miss" - even that when adding SODIMMs to the unused slot pair (2 and 4) one should use modules identical to those in the first pair (1 and 3). This contradicts what I have learned about "Dual Channel" configuration and the way that this concurrency is facilitated (identical modules specifically in the PAIR of slots that are to be concurrently accessed, i.e. 1 & 3 OR 2 & 4). My understanding has been that there is no technical requirement that the modules in one pair must be identical, or even match, those in the other pair (i.e. no reason that ALL four SODIMMs have to match).

It's easy to get confused about (for me anyway) - when I read the tech papers about dual-channel mem architecture etc.., it is explained that the "matching" of dimm's is important if they are in "paired slots" (e.g. slot 1 and 3, slot 2 and 4 - in the 4-slot lappies), makes for "dual-channel" configuration, i.e. concurrent access will occur if identical SODIMMs are used in each channel-pair - memory access will benefit from markedly improved bandwidth. I.e., technically, slots 1 and 3 could be Kingston CL 11-28-28-28 matched sodimms, and slots 2 and 4 could be Crucial CL 9-24-24-24 matched sodimms and they'd still be fully enabling dual-channel.

Nevertheless - actual real-life experience seems to counter this claim after all - from what I've been reading. Some platforms/machines seem to be more finicky or picky about their memory.

I've got a G55VW that I am still loving - (3630QM, GTX660M, etc..); it is the finest laptop I've ever had (not just for obvious generational improvements, either). Anway - I know that my G55 has Hynix (2x4gb, PC3-12800, 11-11-11-28) running at 1.5V (thought they'd be 1.35V). I'm hoping that these are not my only option.

In my search for "compatible" memory, I found that both Crucial and Kingston have their own utilites (flavors of CPU-Z) to assist determination of compatibility. Before I ran their scan utilities, their sites only listed (static content) SODIMMs with identical timings/specs to my system's orig. installed (except that none of them are recommending 1.5V SODIMMs for my G55VW, only 1.35V - which is a little annoying, just for the confusion-factor)... But, more INTERESTINGLY, despite their pre-published "short lists" only showing the identically-spec'd (CL 11---) modules, after I run their scan utilities, they widened the compatibility-criteria substantially: they added their "performance" products to the list of Asus G55VW "compatible/supported" memory, SODIMMS with lower timings like 9-9-9-24 .. in other words, e.g., Crucial's static list of compatible SODIMM for the Asus G55VW only had a single 8gb kit (2x4gb) with identical cas at CL 11, 1600mhz, etc. THEN, post-scan of my system, they expanded the list of compatible modules to include their "Ballistix" branded performance mem, with CL 9--- timing, etc.. and even included some higher-freq PC3-14900 mem (technically, higher-freq mem should work fine at lower speeds I guess)

I realize that the actual experiences of G55 owners tends contradict some or all of this - that there seem to be additional factors that effect whether a particular SODIMM spec or brand will function properly in the G55, and ... well - here I am ;-) It seems that it's a case of "deviate at your own risk".
Incidentally, if there is a list of tested SODIMMs for the G55 (pass/fail or something), I was not successful in locating it, and offer my apologies for that ;-)

So, what should I do...? Try to get some answers, and some advice. ;-)
First Question - since the current 8gb (2x4gb) are 1.5V, and manufacturers are recommending 1.35V - I'm wondering if the second pair can safely be 1.35V... seems intuitively wrong, but I think it might be ok to do this, but with fairly low confidence-level. For that matter, as I understand it, some SODIMMs will can run at either 1.35V or 1.5V... my concern is I'm not tweaking/overclocking or anything. Done plenty of that on desktops over the years, but -- have zero desire to risk my G55 for a few extra cycles...

Hope this wasn't waaay TL;DR --- my desire is to put some decent, fast mem in the two user-accessible slots, like Crucial's 9-9-9-24 (1.35V) or Kingston's "HyperX" equivalent... but do not want to rip the case open to get at the "non-servicable" slots...
If I really ought to stick with 1.5V, then that is what I will do. If I really ought to stick with identical DIMMs to existing pair (why? oh why?), then that, reluctantly, is what I will do. I seek the wisdom and guidance of the experts and/or the battle-scarred who have been here before ;-)

Cheers!

Stephen / aprilia1k

hmscott
12-27-2014, 03:11 AM
Stephen, I would encourage you to read the G75 ( / G55 ) thread that is a sticky for memory addition:

Adding RAM to G75
http://rog.asus.com/forum/showthread.php?23929-Adding-RAM-to-G75&p=168628&viewfull=1#post168628

The G55 is the same as the G75 for memory expansion, so that single thread is enough, but there are other G55 threads that aren't stickies, you just need to do a simple search on

G55vw sodimm

This thread has the right response here:

"The best way to upgrade your RAM is to download CPU-Z and look at the specifications of your existing RAM. Then find some that matches them exactly and you'll be free of problems."

G55vw-RS71 RAM question
http://rog.asus.com/forum/showthread.php?39173-G55vw-RS71-RAM-question&p=329579&viewfull=1#post329579

Even better is to find exactly the same SODIMM, there are plenty of sites online that you can get the same memory at a good price. I use ebay and get laptop pulls, they are already burned in and stable and are cheaper than new.

Adding memory shouldn't be looked at as a mental exercise, it is a simple look, order, and install.

There is no reason to put in so much time into figuring out how to save $5 on some cheaper memory. It doesn't pay off in the end. If you have to "win" then go ahead and play that game, but for me I would rather get the same part the first time and give it no further thought - including after it is installed and you get a random BSOD and have to wonder if the memory you bought 3 months ago is really compatible.

If you want to get faster memory, replace all 4 SODIMM's. I haven't spent time upgrading the G55vw, maybe someone else has found the optimal fastest memory for the G75/G55.

Also, this era of motherboard chipset / CPU uses 1.5v memory.

Here is what the CPU-Z read out looks like for me, and I ordered the same 8GB part from ebay, and installed it with no further thought - except for answering these questions.

44668

Even with an upgrade from 1600mhz to 2133mhz memory in a G750, there wasn't that large of an improvement so as to go through the trouble of replacing all 4 SODIMM's, so I am still running the original memory Asus selected, 4 x 8GB - and I never need to think about it again.

Please post what you have, a nice Windows Snipping Tool screen grab of the CPU-Z SPD page would work, as above. Then do a google search for a new pair to expand your slots completely.

Please post back when you have it running too :)

aprilia1k
12-28-2014, 01:46 AM
I appreciate the response, hm -

I think I must have been unclear, or by saying so much I convoluted my main point.

(btw - 1.35v is definitely supported by this cpu... have to look closer at the m/b. Both Crucial and Kingston claim that their 1.35V SODIMMs are correct for the G55VW.. perhaps they are just wrong). And - money is not the issue for me - it is the generic memory that's already in the machine. I want to use faster mem for the second pair - and as I've explained, there's no technical reason that the second pair has to match the first... if it does - it's a glitch.

I did search and found the threads that you have referred to. What I was trying to say was that, based on what I know, we should not be limited to adding SODIMMs that exactly match the existing SODIMMs. I imagine that my post was just too long. The PAIRED slots, 1 and 3, 2 and 4, should be matched, in order to benefit from dual-channel configuration (concurrent i/o of both channels). BUT... SODIMMs in 1 and 3, technically should not have to match those in 2 and 4. In fact, they don't even have to be at the same voltage... technically. I have been using dual-channel for as long as it's been around (it's not special memory, it is a technology-feature within the controller, that is enabled by the existence of identical modules in the PAIRED slots (again, for these laptops, 1 & 3, 2 & 4).

I don't want to be limited to matching the Hynix 11-29-29-29 4gb SODIMMS that are in the non-serviceable slots, and should not have to be. Any such requirement is a flook of the hardware implementation (i.e. the memory controller, or even the BIOS I'd guess). The spec. makes no such requirement. Again - I know that folks have encountered "no-joy" situations when not matching all four SODIMMs - that's real-world experience, but - it's more of a bug or glitch than a failure to meet the hardware's specs/requirements. My question was whether there were any published/maintained lists of SODIMMs which seem to work when added to the user-serviceable slots. Please know that I do appreciate you taking the time, and mean no offense by expressing dissatisfaction with just settling for what is already in the "warranty-voiding" slots in the laptop. I can get Crucial Ballistix (2x4gb) at 9-24-24-24 for $65 (Amazon), versus over $90 for the generic Hynix (only on ebay so far). So - performance mem that's highly rated for 70% of the price of generic mem is... tempting.
EDIT: That was totally wrong - I must have mistaken something in a google search... the Hynix on eBay is far cheaper than that.... my bad there. Look - you're right, it's doubtful I'd ever notice the perf difference for day-to-day, and probably not even for encoding/decoding vid, etc.. since the first bank would be the original mem anyway. OK - So, I'll probably just take your advice. I've never dealt with laptop upgrades, but this G55 is such a great machine, imho, that it's worth up'ing the memory... My experience is largely with desktops, and lots of them - where "serviceable" area has no meaning ;-) I sincerely thank you for your generosity of time and efforts - and gentle proddings instead of scoldings (re: looking for info, since it looked like I hadn't done any homework). You are a gentleman and a scholar sir.

I may bite-the-bullet and just tear the machine down (void the warranty - carefully ;-) ) ... and replace the stock mem ;-)

Thanks again,

Stephen

aprilia1k
12-28-2014, 02:39 AM
Looks like I spoke too soon - the cheaper Hynix SODIMMs are all 1.35V. Looks like the 1.5V are more rare, and that's reflected in the price. Oh well. (Wish I wasn't put-off by the non-serviceable area.. I know it's just time and keeping track of screws, etc.. -- but, it is offputting) It'll be worth it.. the 8gb to 16gb leap will be very noticeable, as I typically hover in the mid-7gb's "in-use", and experience the joy of swapping a little too often ;-)

hmscott
01-02-2015, 10:37 PM
Looks like I spoke too soon - the cheaper Hynix SODIMMs are all 1.35V. Looks like the 1.5V are more rare, and that's reflected in the price. Oh well. (Wish I wasn't put-off by the non-serviceable area.. I know it's just time and keeping track of screws, etc.. -- but, it is offputting) It'll be worth it.. the 8gb to 16gb leap will be very noticeable, as I typically hover in the mid-7gb's "in-use", and experience the joy of swapping a little too often ;-)

aprilia1k, all good, read it all and still suggest getting the same make / model family 8GB SODIMM's that match the 4GB make/model, or maybe even replace all with the 8GB.

The spec for the SODIMM's will often have an SPD value and a Tested Value, and this can work good/bad in both directions. If your chipset likes 1.5v memory, and the SPD is 1.35v but Tested at 1.5v, it might work ok - or it might not, you don't know until you try - why risk the potential waste of time?

ROG laptop BIOS settings aren't flexible enough to set the voltage manually - usually the BIOS goes by the SPD values.

I would go with SODIMM's with the correct voltage in SPD rather than Tested at the required voltage and SPD at another voltage.

On Haswell, there are memory with SPD at 1.5v and "Tested" at 1.35v that *run* at 1.5v when installed in a G750 because it reads the SPD... and there is no way to override the SPD and run at 1.35v tested...

The G751 seems to be more tolerable with running non-matching make/model memory than the G750.

Often people would come on to the G750 forum complaining that they matched the SPD settings with a different make/model memory - slightly cheaper - and were having black screen no boot or BSOD's since adding the memory. Then after explaining that they can get reliable operation by getting the same make/model memory and shop for the price they can afford - they come back with stable operation.

That is why I suggested you read the forums for your specific laptop model / series as they will have feedback need to know how tolerant the design is to matching, or not matching memory.

Let us know how it works out :)

(please don't forget to delete the post here: https://rog.asus.com/forum/showthread.php?53752-1-35V-memory-required-in-G751-G771-G551s-(same-as-G750)&p=461006&viewfull=1#post461006 it's already generated a response because it is in the wrong place...