Thinkpad's and N100's w/ 945PM chipset can't address 3G Ram but Dell Can

Question

Since I am a programmer, I am particularly interested in having the maximum amount of Ram available under 32 bit Windows.
Unfortunately,  I have to buy a T61p to enable me to use 4GB.
From a reply to a NoteBook review Forum:
http://forum.notebookreview.com/archive/index.php/t-136639.html
At work, we have both Dell XPS and IBM/Lenovo Thinkpad laptops. We choose the T60 models for their compactness/weight and reliability, while we choose the XPS M1710 and M2010 for their 17 and 20-inch screens and somewhat faster graphics chips. The ThinkPad T60 computers have problems accessing over 3GB RAM, and that is NOT because of the chipset or the OS that we use, but, it is only because of the incompetent designers/engineers at IBM or Lenovo; let me explain:
We have tried to install both 32-bit and 64-bit version of Vista, Windows Server 2003 R2 STD, Win XP and different dists of LINUX on T60, T60p, Z61, Z61p, Z61m, (X60 and T43) and Lenovo 3000 series, but they simply can NOT access memory over 3GB (X60 and T43 can not support that since their chipset seem to have accessing issues over the magic 3GB, but we tried anyway)
We also tried the same thing on Dell XPS M1710 and M2010, and they could access almost the ENTIRE 4 GB installed even with 32-bit version of Windows Vista (BTW, 32-bit Vista can access 16 GB RAM with the right chipset so...). Of course, now you can guess that it was no problem with the 64-bit version of the OS:es we tried.
The Dell XPS M1710 and M2010 use exactly the same chipset found in T60 and Z60 series (Mobile Intel 945PM Express Chipset). In December 2006, we even opened a T60p (model 2007 8JG) and compared the chipset with the Dell XPS M1710, and well, I suppose that you have already guessed that it was the same chipset in both machines.
Honestly, I hoped that we would find the Mobile Intel 945 GM or GMS chipset in the T60 laptops (those chipsets seem to have this 3GB limit), since we had a BIG argue with the support guys at Lenovo, and they came with totally silly answers why the computers can not access over 3GB RAM. They even asked me what I need 4GB RAM for!! Can you imagine that?! You can ask ANY programmer/developer who works with virtual machines (both VPC and VMWare or even Parallels) and everyone will tell you that you can not have too much RAM!!! And it IS A BIG difference between 3GB and 4GB. However...
Now, we have heard rumors that HP NX94xx also can access 4GB RAM installed, but I can not confirm it myself, since I have not seen it myself.
And now, regarding to your post about mixing 2GB SO-DIMM with 1GB SO-DIMM, I would not recommend it. The 2GB SO-DIMM memory modules are pretty cheap now, and besides, you will lose a lot of speed mixing 2GB with 1GB memory modules. Just try different benchmarking programs and you will see. If you want to see quick results without a lot of installations, try Memtest86+
However, I think that it is very rotten that IBM/Lenovo does not care about their customers and lets a lot of incompetent technicians answer the phone. I have tried to come in contact with higher bosses and engineers, but they are simply unavailable. But it must be a way that we customers can make them hear us.. I only do not know how! :-/
And so, here ends my first (and long) post in here!
From the thinkpad forum, there is another confirmation, but the author is not aware that Dell did a better job with the P chipset:
T60/T61/p memory limitations -- the definitive answer [pics]  
http://forum.thinkpads.com/viewtopic.php?t=49703
update 10/25/2007:   now includes T60/p information.
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.   if you have a T60/p then installing 4GB total system memory is a waste.   save your money, stop at 3GB, and put the savings either in the bank or toward a T61/p if you want 4GB.
quoted from official lenovo documentation:
Quote: Maximum memory capacity may require the replacement of standard component with largest supported component available. On ThinkPad systems with an Intel 945GM, 945PM, GM965, or PM965 chipset, even though it is possible to physically install 4GB of memory, the actual amount of memory addressable by an operating system will be limited to 3GB. This limitation does not exist with the Intel GM965 and PM965 with the 64-bit operating systems Windows XP Professional 64-bit and Windows Vista 64-bit Editions.
the key point to take away from this quote:   the T60 and T60p are based off of the 945GM and 945PM chipsets and therefore fall under the 3GB physical limitation as stated above.   even with 4GB total system memory and a capable OS, you still can't see or use more 3GB no matter what you do.
T61 and T61p:
the T61 and T61p are based off of the intel socket P processors.   these systems are capable of using up to 4GB total system memory as long as you use the proper OS.   below are the results from the four most popular microsoft OSes tested on my T61p.

Answer 1

i wrote the article over at TPF regarding T60/1/p memory limitations.
while i've read that certain dell models can supposedly access all 4GB, i have yet to see definitive proof backing this up.   from my understanding, dell wrote their BIOSes to report the maximum installed memory but the systems still cannot utilize more than 3GB regardless of what is reported.   dell is the only manufacturer with a 945-based system which claims to use all 4GB so it leads me to think that something fishy is going on.   if the 945 could use more than 3GB then you'd think lenovo, apple, HP, etc. would have been able to pull it off as well.
before buying my T61p i performed weeks of research on the subject of 3GB/4GB limitations in chipsets.   i have yet to find definitive evidence showing that a merom-based system can truly access more than 3GB because of the chipset's lack of memory hoisting capability.   santa rosa seems to be the first mobile chipset supporting memory hoisting (which is necessary for moving memory addresses above the 4GB mark so that all 4GB of physical memory can be addressed by the OS).
the simple solution is to buy a T61p.   while the T60p did have optional IPS displays, the T61/p is better in absolutely every aspect except display quality.   i've had my hands on numerous T60/p systems of friends/family/colleagues and wouldn't trade my T61p for any of them.   my next upgrade won't happen until intel makes a mobile chipset able to address 8GB+ system memory (which santa rosa very well may be able to do but we won't know for sure until 4GB SODIMMs are released for public consumption).
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