Thinkpads Forum

The W540 I just got has two 8GB Samsung sticks of RAM installed-guessing the original. DDR3L-1600. My head says I do not need 32GB for email, surfing, the How-to YouTube video, and some light photo editing-but my heart says why not see how quickly and smoothly it runs (I've already done the Samsung 860 EVO SSD). My question is, do all four sticks need to be the same, or could there be two pairs of matching sticks as long as all four had the same specs? If two pair of matched sticks would work-says two Crucial in addition to the two Samsung, how should they oriented? The two sticks in there now are in slots 2 and 3 according to CPU-Z. TIA

Larry aka CharlieDog

Basically any stick that works will do.
Having 2 matched pairs would be nice but is not really needed.
Most important is that all sticks have the same speed, brand is of less importance, but avoid so-called Value-RAM.

Thanks. That's kind of what I thought. The next question is, does orientation matter? Should one matched pair be in slots 1 and 2, and the other in slots 3 and 4? Or doesn't it matter? TIA

Larry aka CharlieDog

The same applies to W510/W520/W530/W540/W541
https://forums.lenovo.com/t5/ThinkPad-P ... a-p/249257

@RBS - W510/520 have the slots under the RAM cover in the back situated next to each other; so your link applies. The W530 (and perhaps following machines) have those two slots on top of each other (just as with those under the keyboard). So while I presume Slots 0 & 2 are under the keyboard for this machine (0 being upper), I don't know how to distinguish slot 1 from 3. Is slot 1 upper? or lower?

EDIT: My error. The W530 slot on the back *are* next to each other. I just got in there again to put in some memory. My apologies for any confusion.

I guess not all W530s are created equal.

And that Lenovo link above that details which slots are which number is also inaccurate, at least for my recent W530 system.

You still want to populate slots 0 & 1 first and then 2 & 3, but they are numbered different than before (or maybe newer ones are different than mine)

I have a 2441-CQ7 i7 3840QM Quad with 4 slots date 1311, 2013 Nov. It has two slots under the keyboard, staggered on top of each other as one would expect. It also has two slots on bottom under the memory door and these butt against each other. They are not staggered on top of each other as the ones under the keyboard.

I have two 4GB modules and two 8GB modules all the same speed PC3-12800 / DDR3-1600 It came with the two 4GBs under the keyboard and I bought two 8GB modules (and another two to max it out at 32GB).

Here's where the fun part comes in. I'm using HWinfo and CU-Z. Since CPU-Z numbers the slots 1-4 I'll just use the HWinfo numbers since they are same as Lenovo's

When I populated the slots as per the Lenovo link above, I got dual channel but the sizes in the slots were all wrong.

When I only populated what the link says was slots 0 & 1, I got single channel and the slot #s were not what I expected either. Populating the two under the keyboard only, gave dual channel but using slots 2 & 3! So I went to one module at a time and have determined that the following is the correct numbering:

The upper slot under the keyboard is #3
The lower slot under the keyboard is #2
The slot closer to the ultrabay is #1
The lower slot between the HDD and docking connector is #0

So I put both the 8GB modules on the bottom and the two 4GB modules under the keyboard and it now says slots 0 & 1 have 8GB each while slots 2 & 3 have 4GB each. This matched Lenovo's suggestion to have the largest modules in slots 0 & 1.

You can populate only the two under the keyboard and it will give you dual channel and it does not matter the size. I suppose the speed does matter, but all mine were the same speed.


I hope this clears up some confusion because I sure was!

I think Linux tools (...what was it? dmidecode --type 17? don't remember) give useful information. I would think one can populate two slots, run this tool and see which slots numbers got populated

Maybe some RAM slot numbers info may be in the maintenance manual if you can download it from Lenovo.

I think that the two sockets on the underside of the machine are Channels A and B primary sockets. So if you have two pairs of identical SODIMMS, and one pair is bigger, put them in the sockets on the back so that you'll have identical channels A and B. Likewise, a 2nd identical pair (and if not the same size as the first pair, this pair would be smaller) in the sockets under the keyboard. Ideally all four would be the same brand, model, and size, to ensure channel balancing. But if you have two identical channels (say a pair of identical Samsung 8Gb in front and a pair of 4Gb Ballistix under the KB) I suspect that performance won't suffer too much.

Most of the schematics I've found (found for the T530, and the W520, but not for the W530) have a messed up notation. They specify two DIMM sockets (shown as Channel A and Channel B primary on pages 12 and 13) as Normal Socket Primary. Then they have two secondary sockets but one is reverse, the other normal. These are on pages 101 and 102 and are listed as Channel A and B Secondary.

That is:

Listed on Schematic.................Expected
Normal Socket Primary 12...........Normal Socket Primary 12
Normal Socket Primary 13...........Normal Socket Primary 13
Reverse Socket Secondary 101......Reverse Socket Secondary 101
Normal Socket Secondary 102.......Reverse Socket Secondary 102

But I don't understand the setup well enough I suppose. In any case, I suspect that they set up the system so that 2 DIMMs in the sockets on the "easy access" bottom of the computer corresponded to Channels A and B primary. Ideally, those would be identical and would be your largest capacity DIMMs.

I'm negating the issue for my W530 by getting a second pair of 8GB modules from the same place that I got the first pair. All 4 slots will have the same size and speed. But what a PITA to figure this all out.

I ended up doing the same!

And what's even better is that is cost about the same as two 4GB DDR2 modules for a T61!!