Hi, I just bought 2*2GB Crucial PC5300 667Mhz memory to upgrade my T61 which has 2*1GB installed before. Hardware insallation is smooth and easy, I followed every step in the service manual. Then I reboot the computer, BIOS can recognize that it has 4096MB ram installled. My operation system is Windows Server 2008 Enterprise 64bit, which, unlike those 32bit system, I am pretty sure it can manage memories larger than 3GB. In the system, it found and and showed there is 4GB memory, however in other softwares like Everest, CPU-z, or Photoshop, even in task manager they all told me that there is only 2GB of memory.

I was confused, and thinking it could be the problem of the new Crucial memory, then I install only ONE 2GB memory each time. They both can enter the system and be recognized as 2GB. So the new Crucial memories dont have any problem. Then I conbined the old 1GB memory and new Crucial 2GB memory to boot the system. Windows also can recognize 3GB of ram but only 2GB of it can be used. 

It seems 2GB is the threshold of this system, any combination higher than 2GB can be recognized but cannot be used. However it should not be like this since it is Windows Server 64bit, theratically it can manage more than 512GB of memory. What happened? What should I do to eliminate this threshold? Problems of Windows? Problem of T61.

BTW, I have updated the laptop BIOS to the latest version. 07-01-2008

This is the snapshot of the sreen, my Windows is Chinese version but the crucial infomation is in English.

http://farm3.static.flickr.com/2194/2949357419_857717624d_o.jpg

gspot,

"3) disabled the windows virtual memory (now my laptop running solely on real RAM, yeah....)"

Well, OK. Whatever makes you happy.

But, turning off Windows virtual memory is a very bad idea.

What do you think is going to happen if you start three applications, and each one wants 2 GB of memory space. The only way the three applications can each get their memory space is if Windows virtual memory is working.

Centex