Thinkpads Forum

it's been discussed several times. The 32bit OSes can only address up to 4GB of RAM. Once you minus things like video ram and lots of peripherals you end up with less space available to map then total amount of RAM.

Lenovo apparently went a step further and just locked it at 3GB instead of a fluctuating number that would be determined on each boot based on stuff that's connected. Unlike desktops that have their parts there all the time, laptops are generally going through more changes when it comes to whats connected to them.

So yeah, i guess it's almost like having a fast car that can do 180MPH but can only reach to 80MPH because of road limiting factors.

SHoTTa35 wrote:it's been discussed several times. The 32bit OSes can only address up to 4GB of RAM. Once you minus things like video ram and lots of peripherals you end up with less space available to map then total amount of RAM.

Lenovo apparently went a step further and just locked it at 3GB instead of a fluctuating number that would be determined on each boot based on stuff that's connected. Unlike desktops that have their parts there all the time, laptops are generally going through more changes when it comes to whats connected to them.

So yeah, i guess it's almost like having a fast car that can do 180MPH but can only reach to 80MPH because of road limiting factors.

But locking it should not affect whether a T61 runs in dual channel sync mode if you happen to have a matched pair of 2Gb modules .... right?

ducky2802 wrote:I had the 2x2gb installed. It sometimes would cause random error messages of the nature that the memory was out of bounds and could not be read. No big deal, but then I decided to split the 2x2GB and the 2X1GB across two machines into the 1X2 and 1x1GB. Havent seen any error messages since, and really havent noticed a speed drop between 4GB and 3GB in xp pro.

ducky .... were these random memory errors on a T60 or a T61?

I also got random crashes using 2x2GB G-Skill CL4 memory on my x60s (which is basically the same as the T60). At that point I thought this is due to using CL4 memory, not due to the 4 GB, but this was just a guess.

I returned the memory and am using the old 1.5 GB setting again. After reading this and other threads, I'll try again with one additional 2 GB CL5 module and I'll be on the safe side.

Maybe someone can help me understand. Vista 64 bit says my T60p has 4.00 GB. Is it lying and only 3 is actually available?

I have not had random memory access errors. I also ran windows memory test and it passed 100%.

You're using a 64-bit OS while the hard limit was only on 32-bit

Yes - I know, the T60 cannot see 4GB of memory. With 4GB installed, only 3GB is visible regardless of operating system.

T60 and T60p:
the T60 and T60p are based off of the intel socket M processors. no matter how much memory you install in these thinkpads, only 3GB will be addressable regardless of operating system used. this is a physical limitation and there is absolutely no workaround.

Is this not a contradiction to my screen shot?

.

So the conclusion is that I am only utilizing 3GB even through it shows me 4GB.

I guess there is no point in running Vista 64 then and I can go back to 32.

[quote="whizkid]

The T61 has a 4GB limit, so if you run 32-bit Windows on it, you'll get to use 3.25 or 3.5 GB of RAM, but you can use all 4GB on a T61 if you use a 64-bit OS.[/quote]

Are you absolutely sure about that? I tested two 4GB modules in my T61p and both BIOS and Vista64-bit could recognize 8GB.....

It's been proven that the 965 chipset can run 8 GiB, even though 4 is claimed.

Anyway, there are solutions to allow access to RAM that has been mapped in I/O space, and use it as a RAM disk on an i945 machine?

Now, here's where it gets downright funny. Put your swap file in your RAM disk. (That approach probably wouldn't work in my case, though - I use a crapload of RAM.)

Can someone try? One forum I'm on linked to this: http://www.superspeed.com/desktop/ramdisk.php

bhtooefr wrote:Anyway, there are solutions to allow access to RAM that has been mapped in I/O space

Short answer is no.

Long answer: the i965 (Santa Rosa) chipset used in T61 has additional registers that allows remapping of memory to an area above the 4GB mark. Therefore, T61 can use the whole 4GB or 8GB when running a 64-bit OS.

The i945 (Napa) chipset in T60 does not have these registers.

My point was more that this approach may work on i945 without remapping anything.

Creating a software RAM disk out of a region of system memory does not change how the physical memory is accessed. Ultimately, memory are accessed by address ranges, because it is the only way the processor can read/write it.

There exist PCI cards that take SDRAM modules and presents itself as a storage device to the systen. These hardware based RAM disks are accessed as a disk, not system memory, and are not subject to the 4 GB limit of 32-bit platforms.

I was under the impression that it was somehow accessed in a different way that bypassed the limitations of the regular address space.

Stucco wrote:So the conclusion is that I am only utilizing 3GB even through it shows me 4GB.

I guess there is no point in running Vista 64 then and I can go back to 32.

Are you sure? Have you verified it on task manager?

ginopilotino wrote:Are you sure? Have you verified it on task manager?

It's been documented time and time again that it's 3 gigs max, and Vista lies. Proof: http://support.microsoft.com/default.aspx/kb/946003

I've just installed the new 64-bit release of the openSuse Linux release in my T60 (2007WXU) that I've loaded with (2)2-gb modules.

And how much RAM memory does the 64-bit OS recognize?

3gb.

Can a T61 really support 8GB of ram, are there 4gb 667mhz modules available.

rssb wrote:

Can a T61 really support 8GB of ram, are there 4gb 667mhz modules available.

Yes and yes.