Laptop: Memory dual channel? 4+8GB?

Hi! I'll get a i7-4702mq with integrated graphics Thinkpad L440 soon with 4GB memory, and I've some questions

I always heard about mixing different memory will cause problem, but I feel it could be something from the old days. I cannot find a definitive answer for these questions.

1) would mixing 2 memories of different CAS latency(almost aka different manufacturer) make a significant difference?
2) would mixing 2 memories of different capacity make a significant difference?
3) how about both 1) and 2). Any effect on dual channel?
4) given how advanced the memory technology is, is dual channel still matter?(I've read that dual channel will still double the memory access speed, but the latency did not change)
5) how would the dual channel thing affect integrated graphics performance on memory part. Is it mainly restricted by memory bandwidth or memory latency?

Please excuse me in my ignorance in memory and thanks in advance!

I'm a college computer engineering student and a crazy multitasker. I do not do graphical design.

Previously, I occasionally ran into extreme of my 8GB memory(I turned off page file). I had a 1333+1600 dual 4GB but I don't have the 1600 anymore. Now I've some thoughts for my upcoming new laptop:

a)add a 4GB-1600MHz memory, cost about $45 and get a total of 8

b)add a 8GB-1600MHz memory, cost about $75 and get a total of 12

 

Get the 12GB RAM option - if you can't do 16GB+ (ideal).

Getting matched RAM does affect the system's stability - for the low cost of RAM vs. the total cost of the system, cheaping out here makes no sense - especially if you're unlucky enough to have the combination of hardware, BIOS, O/S and software that leaves you scratching your head as to why your system is glitchy/not stable.

The examples you'll hear that 'but it works for me' will be no consolation when it does not work for you.


Good luck.

 

I have mixed RAM in one of my laptops (different brands, and iirc different timings too, though both are 1333MHz) and it has caused exactly zero problems with that laptop.

Really, the only thing that truly matters with RAM would be how much you have, so the more the merrier. Higher RAM clocks (like 1866MHz or higher) would somewhat help with iGPU performance, though if you're looking for GPU performance, why not just get a laptop with a dGPU (with much, much faster VRAM)?

 

There is no issue with stability with mixed RAM sizes. It will run asymmetrical dual channel and offer little to no degradation in performance.

 

Mixed latencies(column address strobe-cas) and the rest of the timings is not an issue, the memory controller auto negotiates thru spd jedec( not xmp-non jedec settings-these are self set at users risk )and chooses the the timings that match, generally lower slower timing,,auto negotiation is patterned after what itt/att hard programmed(cannot be flashed up or down)modem chips do with the servers-----they set the speed by automatic negotiation,,Thats why vendors squawk about buying sets as there timings are exactly the same for featured speed in dual channel mode-ect,,cas-9,10 ect..If you know your models timings(cpu-z will show you) you can buy another module(same size) from a different company even and dual channel is active. I have dual channel active with two different memory companies in Lenovo G530-already sold...The more memory the better is quite true running programs thru ram rather than pagefile is much , much faster,,I have PC3-14900 (2x8GB)1866Mhz-16GB in bound Crucial Ballistix Sport for my new laptop, the CPU that has the 1866Mhz memory controller integrated in the APU is inbound as well..You can buy one or sometimes two steps higher frequency ram than your memory controller as auto negotiation will set the max of the memory controller--check the specifications out of your memory controller and the ram chip plug n play(not plug n pray,,lol) jedec timings for spd and xmp available.

Note XMP is an Intel extension , not a supported JEDEC standard*.

*- See link below

Cheers
3Fees

Note different size mem modules on intel chips will still run in dual mode ,yet only to the size of the smaller mem mod , this is flex mode.
No fumbleleina's.

Update:
Heres something new about ram I just found , thankfully its vendor specific..

*Vendor-specific memory(*-see link below)

A common misuse is to write information to certain memory regions to bind vendor-specific memory modules to a specific system. Fujitsu Technology Solutions is known to do this. Adding different memory module to the system usually results in a refusal or other counter-measures (like pressing F1 on every boot).

02 0E 00 01-00 00 00 EF-02 03 19 4D-BC 47 C3 46 ...........M.G.F
53 43 00 04-EF 4F 8D 1F-00 01 70 00-01 03 C1 CF SC...O....p.....

So it appears that some Fujitsu systems will only take Fujitsu approved memory...Talk about going backwards..

http://en.wikipedia.org/wiki/Serial_presence_detect

 

Cause I'm not a serious gamer. I do starcraft 2 occasionally on weekends(since college is busy), I don't need the dGPU, but it'd still be nice to improve the iGPU in some degrees.

That's good to know, thanks!

 

Something else to be aware of is DDR3L and DDR3, 1.35V vs 1.5V

 

Right, that is extremely confusing due to mislabelling of manufacturers.

My 4702mq only supports(?) 1.35v DDR3L and the laptop came with DDR3L.

However, Crucial sells 1.35v/1.5v dual voltage DDR3(that's what the name is) RAM and 1.35v DDR3 memory, which doesn't sound right. Once they support 1.35v, shouldn't they be considered ddr3l?

as far as I recall DDR3 regular only supports 1.35v?

Can I use 1.35v DDR3 memory on DDR3L? is the difference is only the voltage?

 

Update Got my PC3-14900 (2x8GB)1866Mhz-16GB Crucial Ballistix Sport in and installed, these are 1.35V modules,,,went in booted right up running 2x8GB timing 9-9-10-28-40 at 1600Mhz,,when my new processor arrives with its 1866MHz memory controller, I'll install and run at 933MHz x 2=1866Mhz. 16GB is sweet. I have HP Pavilion 17 " AMD Elite A8-5550M-8550G,,new processor is AMD Elite A-10 5750M-8750G ,,the crucial modules show both Jedec and XMP timings using CPU-Z,,XMP-1866 tops out at 933MHz 10-10-10-30-45-2T,,Jedec #8 1116Mhz(2232Mhz) 12-12-12-38-55, Jedec #9 shows 1209Mhz(2418Mhz)12-12-12-38-55,,clearly Jedec timings are superior to Intel xmp extensions,,xmp is not certified by Jedec. Jedec settings are for the most compatibility,,,,

HP says my notebook runs 8GB max..I knew they meant 8GB per memory slot,,,,,HP Pavilions 17.3"(2013 model I have) upgrade to (2x8)16 GB..

Cheers
3Fees

From what I have read 1.35V/1.50V can be used,,Crucial Ballistix Sport are designed to run at 1.35V,,go crucial ballistix sport. The difference between 1.35v and 1.5v is heat,,1.35V runs cooler, notebook runs cooler.. 1.35v/1,5v modules will run at 1,35V if both are 1,35V if one is 1.5V both will run at 1.5V.

Cheers
3Fees

 

My Vaio S13 came with 8GB of memory (4GB soldered on board) and I ended up using Samsung's documentation on the naming conventions of their individual memory chips to find the model number of an 8GB module that would have the most closely matched chips to the soldered memory in terms of specifications but to be honest I'm sure it doesn't matter too much. I'm just a bit obsessive.

 

There are DDR3L 1.35V modules that are backwards compatible with DDR3 1.5V.

Unless you know for sure your Haswell laptop will run with DDR3 1.5V without problem then IMO stick with DDR3L. I have heard of people buying extra memory which was DDR3 1.5V to add to the existing DDR3L memory in their laptop only to have the laptop fail shortly afterwards, that is the mainboard/cpu failed. Whether it was directly a result of DDR3 I don't know.

MSI Global – FAQ

Upgraders: 1.35V memory is required!