4GBs in Dell XPS, why not in ThinkPad T60? /same chipset/

[Dimitri_P]

My friend found this online:

http://blog.venthur.de/2007/05/14/4gb-ram-on-a-t60/

short excerpt:

"Dell sells computers with the same chipset found in Thinkpad T60, and Dell computers (Dell XPS M1710) have no problem at all accessing 4 GB RAM. We have many Thinkpad T60 Z61p X60 (almost all Thinkpad “60″ models) and some Dell XPS M1710 laptops, and we have even opened the computers to compare the chipsets; both Dell and IBM/Lenovo use the same type of chipsets, and Dell:s construction can access 4 GB installed RAM, but IBM/Lenovo can NOT. We have tried 32 and 64 versions of Vista, Windows Server 2003, and different dists of linux on both systems. No problems at all on Dell and the XPS 1710 shows shows 4 GB RAM while the Thinkpads show only 3 GB."

So what do we think about that?

/T61 is also limited to 3GB, reading article?

[bitvector]

If the chipset does indeed support that, then this would be an issue of the BIOS not enabling or allowing you to enable "memory hoisting" support, which modifies the system E820 memory map so that the occluded 0.5-1GB of physical memory appears at physical addresses higher than 4GB (see the diagram here for a picture).

Now why wouldn't it allow this if the chipset supports it? Either the BIOS authors are lazy or it is a physical limitation specific to IBM's hardware. Since the Pentium Pro days, most x86 CPUs have had 36-bits of address lines, but sometimes they leave the top 4 bits unconnected on the motherboard to save power or money.

[Dimitri_P]

I understand logic behind it, but still if Dell can do, why can't Lenovo?

If there is same crap of 3 or 3.5GB on T61; I don't necessary see the reason to buy itl other than a "new toy"

[Troels]

Exactly. I was just about to comment on the PAE.
The address space must of course be needed in the 32 bit space for other pheripherals, so Intel invented the PAE (Physical address extension, i think) since the Pentium Pro days.
It seems as if this just isn't enabled - due to stupidity? Who knows...

I'm not so sure why he raves so much about "Dell", when it obviously doesn't apply to many models, or maybe only that one. I've helped out a guy who bought 6 GB with his Dell desktop, but he couldn't understand why only 3,070 MB was available. He didn't take it nice on Dell when I explained it to him.

[Dimitri_P]

I put 4GB in T60;

without /PAE, I could only see 3GB in Vista 64bit; not even 3.5GB - elaborate on that please

[Troels]

Actually, the PAE has been disabled in 64 bit editions of Microsoft OSs. The command/parameter will work, but won't do anything.

Do you see more available memory when using the /PAE parameter?

I also believe the chipset must enable PAE, as it is both a hardware and a software feature. If it isn't physically implemented in the hardware, the software won't help.

[bitvector]

I also believe the chipset must enable PAE, as it is both a hardware and a software feature. If it isn't physically implemented in the hardware, the software won't help.

PAE is something enabled by the OS and supported by the processor. PAE lets a 32-bit OS address physical memory up to 36-bit addresses.

[tomatoeblue]

The limitation has been removed with the T61, so with T61 it is possible to use the full 4 gig ram if you have an OS that is capable of it.

The poster on that site who's complaining about not being able to use 4 gig with T61 is trying using 32bit windows.

[tomh009]

T61 is also limited to 3GB, reading article?

Reading the blog replies ...

I just got my T61 (yes Johnny - they we also have a problem with T61 models) and playing around with it’s 3G/4G memory problem, tried every possible solution that i dig from the web… nothing works!!! (...)

Oh, Johnny, The only thing that I didn’t try is setting up a 64 bit OS on my T61 - The system came in with 32 bitvista OS.

Well, duh! You need a 64-bit OS to see 4 GB. And we now have seen numerous posters with Santa Rosa-based ThinkPads who see the full 4 GB with 64-bit operating systems, so there is no issue with the new models.

Old models (T60/R60/X60)? Yes, the Lenovo BIOS uses a full GB for I/O, but most other implementations use between 512 MB and 1 GB as well.

[Troels]

You don't need a 64 bit OS. You just need one that has PAE enabled, or allows PAE to be enabled.
I've found, by digging in MS' long and confusing webpages that PAE is standard since WinXP SP2 and that the /PAE argument has no function anymore.
http://en.wikipedia.org/wiki/Physical_Address_Extension covers the basics and a little more.

[bitvector]

A 64-bit OS is neither necessary nor sufficient to see the full 4GB.

You need two things:
* An OS that can address > 4GB of physical memory (64-bit does this as does 32-bit with PAE).
* BIOS support for memory hoisting so that part of your physical memory addresses are moved out of the way of device addresses.

If you have a 64-bit OS, but not the second, you'll still only see 3.0/3.3/3.5GB (depending on how much is "occluded").

[tomh009]

PAE is just as much of a hack as the original Intel x86 segment registers (had IBM chosen the Motorola 68000 for the original PC, life would have been much easier back then), and using that extra memory requires that the applications implement the AWE APIs -- which, in practice, almost no one does.

Whether Lenovo's BIOS supports access to memory over 3 GB is really of no more than academic interest as PAE is irrelevant in the real world. If you want 32-bit, run a 32-bit OS and accept the limitations. If you want to overcome those limitations, install a 64-bit OS.

[bitvector]

Whether Lenovo's BIOS supports access to memory over 3 GB is really of no more than academic interest as PAE is irrelevant in the real world. If you want 32-bit, run a 32-bit OS and accept the limitations. If you want to overcome those limitations, install a 64-bit OS.

You are confusing two different things. The BIOS feature of "memory hoisting" or "memory hole" or "remap above 4GB" has nothing to do with PAE. As I said in the post before, without the ability to map the physical memory addresses that would normally be occluded by device addresses above the 4GB line, you cannot use the full 4GB even with a 64-bit OS.

[tomh009]

You are confusing two different things. The BIOS feature of "memory hoisting" or "memory hole" or "remap above 4GB" has nothing to do with PAE. As I said in the post before, without the ability to map the physical memory addresses that would normally be occluded by device addresses above the 4GB line, you cannot use the full 4GB even with a 64-bit OS.

And with a new *61-series ThinkPad, you can use the full 4 GB.

[tomh009]

A 64-bit OS is neither necessary nor sufficient to see the full 4GB. You need two things:
* An OS that can address > 4GB of physical memory (64-bit does this as does 32-bit with PAE).

Just to close this loop: Windows XP SP2 with PAE will still only have 4 GB of physical address space. To get more than 4 GB with PAE, you need one of the server operating systems.

http://www.microsoft.com/whdc/system/pl ... ae_os.mspx
http://support.microsoft.com/?kbid&id=888137

[verbs]

You are confusing two different things. The BIOS feature of "memory hoisting" or "memory hole" or "remap above 4GB" has nothing to do with PAE. As I said in the post before, without the ability to map the physical memory addresses that would normally be occluded by device addresses above the 4GB line, you cannot use the full 4GB even with a 64-bit OS.

And with a new *61-series ThinkPad, you can use the full 4 GB.

So you are saying that since I have a T61, all I need is the 64-bit OS and I will be able to use all 4GB?

[tomh009]

Yes. You'll get something like 4022 MB available.

See this thread, for example:
http://forum.thinkpads.com/viewtopic.php?t=44764

[verbs]

Yes. You'll get something like 4022 MB available.

See this thread, for example:
http://forum.thinkpads.com/viewtopic.php?t=44764

Wish I would have known or else I wouldn't have wasted my $$$$ on the 2GB 2DIMM setup. Thanks.

[carbon_unit]

Sell one of them in the Marketplace and buy a 1GB SODIMM to replace it.

[Troels]

A 64-bit OS is neither necessary nor sufficient to see the full 4GB. You need two things:
* An OS that can address > 4GB of physical memory (64-bit does this as does 32-bit with PAE).

Just to close this loop: Windows XP SP2 with PAE will still only have 4 GB of physical address space. To get more than 4 GB with PAE, you need one of the server operating systems.

http://www.microsoft.com/whdc/system/pl ... ae_os.mspx
http://support.microsoft.com/?kbid&id=888137

It doesn't seem very clear - why would it only have a 4 GB address space compared to a 64 GB space, I see that they are summing it up in their table, but after reading everything in those links, i didn't see a clear explanation.

Is it because of the way their "secret" DEP has been implemented?

[erik]

And with a new *61-series ThinkPad, you can use the full 4 GB.

what about windows 2003 server standard + SP2?   would it see the full 4gb?

[tomh009]

I haven't seen anyone test that combination.

But why would you want to run Server 2003 and PAE anyway, on a notebook?

[erik]

i build websites and need to host multiple clients' sites locally for development.   vista supports this but i'm gun shy on making the switch due to driver issues.   server 2003 has proven to be bombproof on my T42p and i can't afford any downtime sorting out vista problems.   i'm about to get a T61p and want to make sure i can use all 4gb with 2003.

[tomh009]

You could always try Server 2003 R2 64-bit ... that's what one needs to run Exchange server these days anyway. Don't know what the driver availability is like, though.

[erik]

if i'm going to spend more money on a server OS, i'll just wait for 2008 to be released.

in the meantime i'll do more homework on server 2003's support of 4gb.   microsoft says that it can see all 4gb but many here say that only 3, 3.25, or 3.5 will be available.   i'm thoroughly confused.

[tomh009]

You could always start with 2.5 or 3 GB (the standard memory from Lenovo, plus an extra 2 GB module) and run that with a 32-bit OS. Then add a second 2 GB module at the end of the year when Vista 64-bit SP1 and/or Server 2008 are released (and when the modules will be cheaper yet).

2.5-3 GB is still not so bad.

[summa]

if i'm going to spend more money on a server OS, i'll just wait for 2008 to be released.

in the meantime i'll do more homework on server 2003's support of 4gb. microsoft says that it can see all 4gb but many here say that only 3, 3.25, or 3.5 will be available. i'm thoroughly confused.

I can say definitively that Windows Server Standard Edition 2003 SP2 can see and report 4GB of RAM. We have several IBM servers configured this way (we did have to enable PAE to get the full 4GB). I have no idea if you'll get the same results from a T60.

[erik]

I can say definitively that Windows Server Standard Edition 2003 SP2 can see and report 4GB of RAM. We have several IBM servers configured this way (we did have to enable PAE to get the full 4GB). I have no idea if you'll get the same results from a T60.

hopefully /PAE does the trick and doesn't cause any application instability with illustrator or photoshop.   roughly $275 from crucial gets me 4gb, otherwise it's only slightly more from lenovo on EPP.   i don't know the latency of the lenovo-tested chips though as they might be a bit faster.

anyway, i'll probably just get all 4gb for now even if part of it goes to waste.   it would give me a good excuse to set up a dual boot with server 2003 and vista ultimate 64 for testing both client projects and my own.

[tomh009]

I think we (as T60 users) should make up a petition to Lenovo to recode the BIOS on the T60 series so that the full 4GB of memory is addressable.

You can petition them, but the business rationale is not there for Lenovo to do significant T60 development work at this point in time. So I really don't think it's going to happen ...

[bitvector]

I think we (as T60 users) should make up a petition to Lenovo to recode the BIOS on the T60 series so that the full 4GB of memory is addressable.

As I said in my first reply, it's entirely possible they cannot do it for physical reasons. Even though the chipset itself may support memory remapping, it requires the utilization of physical addresses greater than 32-bits. The processor has 36 separate address lines so it can generate these addresses, but it's possible the top four lines aren't actually connected to the northbridge so they're always interpreted to be 0. In that case, there's no way you can get all 4GBs because the physical address range is limited to 4GB total and part of it will always be occluded. You can't remap because there's no way to access the remapped memory. To quote Doug Cook's MSDN blog, "many motherboards (especially on laptops) only have 32 address pins connected."