Thinkpads Forum

It was brought to my attention that certain W510 now appear in the Tabook as having only two memory slots instead of four.

The models are: 4319-5RU/5SU/5XU/65U (page 73), 4389-P2U/P3U/P9U/PAU (page 75) and 4391-P2U/P3U/P9U/PAU (page 77).

Also, for these models the memory controller is listed "up to 1066MHz" instead of "up to 1333MHz".

Interestingly, the change seems to have happened in the latest Tabook update. I have an older issue of the Tabook, and the exact same models say "4 slots, up to 16GB".

Does anyone know more about this? In the HMM I found no reference for W510 which may contain a different number of RAM slots, and the mentioned models are not referenced in the HMM at all...

W510's have become available with dual core processors, they only support DDR1066, and maybe they decided to strip these models of two of the memory slots as well.

I remember reading that the dual core CPU's only supported two DIMM slots while the quad core CPU's supported four DIMM slots.

I do not know if the above is correct. However, when it comes to multi-socket motherboards, an additional socket doubles the number of available DIMM slots.

Quad core CPU's on notebook computers can have up to 4 slots RAM.

Dual core CPU's on notebook computers (including the i7-620DM dual core) can only have 2 slots RAM maximum.

Interesting, do you have some reference explaining that?

I wonder if it means that they use a different board with only 2 slots, or maybe they use the same board with 4 slots, but only 2 can be used? If that's the case, than changing the CPU at a later point to a Quad may make the 4 slots usable.

Well... one thing that would have to be different if they are core 2 duos, is the chip socket... which means they may have a different motherboard completely... and so you wouldn't be able to put in that much memory... but that's still just speculation.

According to this, the dual and quad-core mobile Core i7 CPUs use the same socket (µPGA-988). As far as the i5, this lists the 520M as using µPGA-988 and the 560M as using µPGA-989, so either this is the same socket, or the i5 CPUs are not even compatible among themselves (and I would find it strange that Lenovo would issue a special board edition just for this one CPU).

Now that Lenovo has refreshed the T410/510 models with Optimus, maybe they did the same to the W510?
It would make sense since i7 quad core models don't have integrated graphics, but the dual core versions do.

wikipedia is about the last place to look for correct processor specs.   the W510 uses a PGA988 socket for all of the current processor options whether it's i-series M, QM, or XM.

both the i5-520M and i5-540M are listed by intel as PGA988 for socketed applications.

520M: http://ark.intel.com/Product.aspx?id=47 ... .40+GHz%29

560M: http://ark.intel.com/Product.aspx?id=49 ... .66+GHz%29



as far as i can tell, the only difference in W510 planars is the inclusion or exclusion of TPM and RAID functionality.   given the MTM numbers listed with cross-compatibility, i'm not seeing anything that specifically mentions a planar with only two memory slots.

http://www-307.ibm.com/pc/support/site. ... 45.html#15

having not used a W510 configured with an M processor, i don't know.   i've only used a QM configuration.

erik wrote:wikipedia is about the last place to look for correct processor specs.

I respectfully disagree. While they are bound to have some errors, I have consistently found their lists to be very extensive, often more complete than what's available on Intel's site, and definitely more conveniently organized.

oh my mistake, thought you meant core2s not i5/i7 2 cores... And yes you are correct for the most part most of the i5s and i7s are same socket PGA988.

I thought the memory capacity on these were based on the memory modules themselves? I'm probably wrong on this but would like to know for sure.

Any chance Lenovo 'decontented' a few models, chiseling away on costs a bit?

Tough pc market out there these days.

Unless it is to remove the GPU component, I would think it'd be more expensive to change the factory line.

To the list of 2-memory-slot W510 models, you can add the "4318" model that you can currently configure with the i5-560M or i7-620M dual-core processors, on Lenovo's U.S. site. See here for more info. Unfortunately, even the Lenovo sales staff apparently thinks the machines have 4 memory slots -- at least that's what they're reportedly telling customers who call and ask.

If the CPU sockets are the same, I would look at the exact chipset being used for the dual-core vs. quad-core W510 machines. For example, although the W700 and W500 are very similar in many respects, the fact that the W700 has no switchable graphics is due to the different Intel chipsets used by the two models.

QFoam wrote:To the list of 2-memory-slot W510 models, you can add the "4318" model that you can currently configure with the i5-520M or i7-620M dual-core processors, on Lenovo's U.S. site. See here for more info.

This is a very good link you provided, since it answers the basic question I have - it's more than a matter of the dual core CPU not being able to address more than two sticks - Lenovo actually did not wire the two extra slots, so even if you were to upgrade to the quad core CPU, you would not be able to use 4 RAM sticks with the same motherboard.

Probably not such a deal breaker for most users, since I imagine very few would fall into the category of having bought the laptop originally with a dual-core and having later decided they want to upgrade to quad core.

QFoam wrote:Unfortunately, even the Lenovo sales staff apparently thinks the machines have 4 memory slots -- at least that's what they're reportedly telling customers who call and ask.

That's not surprising. It's a small and moot point, and the sales staff has consistently shown themselves to be clueless in many technical aspects of the things they sell. I would be actually more surprised if they knew the answer to this one.

I'm not sure about the post made on the Lenovo forums... but the amount of memory you can put into the system is limited to the type of memory modules, and the dual cores can only go up to 800/1066Mhz chips, while the quad cores 1333Mhz. From my understanding it's the memory modules that allow for the capabilities as there is plenty of addressable bits by the CPU.

When I called the sales support, I did want to clarify the 4318-CTO were identical regardless of the configuration I made, so if I did swap the CPU (which I did to the i7-940XM), the system would have 4 memory slots. She assured me that all the links on Lenovo's site to the W510s were the same machines just w/ different configurable options by default for the users to pick from. So it worked fine after swapping the CPU and adding 16gb RAM (4x4gb).

From most people it seems they are always having this problem with a dual core cpu.

QFoam wrote:If the CPU sockets are the same, I would look at the exact chipset being used for the dual-core vs. quad-core W510 machines.

According to the tabook, the chipsets are the same. The integrated memory controller of the processor determines the max speed at which it can access memory. As playersnoopy indicates, the address spaces are the same between the processors. But as far as the number of memory slots goes, whether there are two DIMM slots or four seems to just depend on the board design. I didn't see anything in Intel's processor spec sheets that specified limits of two or four DIMMs for the integrated memory controller of the i7-620M or i5-560M. Presumably, two slots is just cheaper to implement than four, plus this causes the dual-core machines to compete less with the quad-core machines, so perhaps there are marketing reasons involved.

So the max memory supported by Lenovo is 8GB for the 2-memory-slot W510 models. Whether you'll be able to get two 8GB DIMMs to work in them is a reasonable question, and should depend to some extent on the BIOS.

P.S. - Here are the specification documents for Intel's Core i5 and Core i7 mobile processors, if anyone wants to do some digging. Perhaps you'll find something that I missed.

Also, here's Intel's own comparison chart of the i7-720QM and i7-620M specs, which gives no hint that I can see indicating that one should support 4 memory slots, and the other only 2.

[url=http://download.intel.com/design/processor/datashts/320765.pdf]Intel® Core™ i7-900 Mobile Processor Extreme Edition Series, Intel® Core™ i7-800 and i7-700 Mobile Processor Series Datasheet – Volume 1[/url], page 20 wrote:The integrated memory controller (IMC) supports DDR3 protocols with two, independent, 64-bit wide channels each accessing one SO-DIMM.

So they don't officially support more than 2.

Vempele, that document is for the i7-700, i7-800, and i7-900 series processors. And we already know that Lenovo provides 4 memory slots in W510 models containing those processors. (And the passage you quote describes how many DIMMs the memory controller can access AT THE SAME TIME, and not the TOTAL number of DIMMs the controller can access -- so it's describing dual-channel memory access.)

What we're trying to figure out is whether there's a technical reason why the i5-560M and i7-620M processors would be limited to using just two memory slots. Which still appears to be an open question.

But I commend you for digging through the documents!

QFoam wrote:Vempele, that document is for the i7-700, i7-800, and i7-900 series processors. And we already know that Lenovo provides 4 memory slots in W510 models containing those processors. (And the passage you quote describes how many DIMMs the memory controller can access AT THE SAME TIME, and not the TOTAL number of DIMMs the controller can access -- so it's describing dual-channel memory access.)

Oops, I should have quoted the rest of the paragraph (can't copy/paste for some reason):

It supports a maximum of one, unbuffered non-ECC SO-DIMM per-channel thus allowing up to two device ranks per channel.

And later,

The system memory controller supports only one SO-DIMM connector per channel.

FWIW the System Memory Interface section is nearly identical in both documents, the only difference is support for DDR3-1333 (which the dual-core processors lack).

Okay, now we're getting somewhere. I like p.22, section 2.1.4 Rules for Populating Memory Slots, which you quote:

"The system memory controller supports only one SO-DIMM connector per channel."

So all the i7-700, i7-800, and i7-900 series mobile CPUs have two memory channels, and they can be accessed simultaneously (thus giving you dual-channel memory). And each channel can support at most one SO-DIMM connector TOTAL. And each SO-DIMM can be "dual-rank" (meaning the memory is broken into two blocks).

For those of you who are interested, here's physically how the CPU would then be limited to accessing a TOTAL of two SO-DIMMs. Let's start with the first of the two memory channels, memory channel A. Each of the two "ranks" of a SO-DIMM must be specifically selected when that rank is to be accessed, by triggering one of two "chip-select" pins on the SO-DIMM. Triggering the first chip-select pin accesses the first rank (or block of memory) of the SO-DIMM. Triggering the second chip-select pin instead accesses the second rank (or block of memory) of that SO-DIMM. And those two chip-select pins, in turn, are driven by chip-select pins coming from the CPU. So what Vempele's passage from the document is telling us, is that the CPU only has two chip-select pins for memory channel A, which I believe will be called SA_CS#[0] and SA_CS#[1] somewhere in Intel's docs.

Likewise, for memory channel B, the CPU will have chip-select pins SB_CS#[0] and SB_CS#[1], which will access the two ranks of the SO-DIMM connected to that memory channel.

And that's precisely what's meant by "The system memory controller supports only one SO-DIMM connector per channel," from a hardware standpoint. And I've seen precisely these pinouts for an embedded version of the i7-620 processor, called the i7-620LE. So it should be safe to assume that the same holds for the i7-620M.

But the interesting part is that Lenovo, HP, and other manufacturers work their way around the above limitation in some manner, because we know that the W510 has 4 memory slots for all of those machines containing quad-core processors, like the i7-720QM for example. So the question then becomes "why aren't they using the same workaround for processors like the dual-core i7-620M in the W510?"

Is there some technical reason why that workaround won't work with the i7-620M? One possible explanation could be that the i7-620M is a lower-power device than the i7-720QM, meaning it consumes a maximum of 35 watts of power instead of 45 watts. So the pins on the i7-620M for address and data lines, which go to the SO-DIMMs, may only be able to drive a total of two SO-DIMMs instead of four.

Or maybe it's just an agreement between the laptop manufacturers and Intel, that they won't produce any 4-memory-slot dual-core laptops. That would limit competition between Intel's dual-core and quad-core processors in laptops. Anyway, the above is my best understanding of how all of this works.

Good work Vempele!