Lenovo 3000 J115 Memory/RAM Problem

Question

Hi everyone. According to the Lenovo website, the Lenovo 3000 J115 machine type 7387 is capable of 4GB of RAM. It has two DIMM slots and supports single or dual channel DDR2 memory. I really wanted to run with 4GB of RAM and it was a deciding factor when I bought the machine.
I purchased two 2GB DDR2 memory sticks, put them in the machine, and the BIOS only shows 2.5GB. The machine runs fine like this, its just not using the memory.  There doesnt seem to be anything in the BIOS to help me out with this. I saw some other people had similar issues with other manufacturers machines, but they only needed to enable something called Memory Remapping in the BIOS to fix the problem. There isnt this feature in my BIOS. I installed the latest BIOS hoping that it would help, but it didnt. I also tried a 2GB and a 1GB memory stick just to see what happens and it still shows 2.5GB even with 3GB of RAM installed.
Does anyone know how to get this machine to recognize 4GB of RAM, or even 3GB of RAM. I called support and at first they were trying to tell me it was a problem with Windows XP. Hmmm....I already told them I was running Windows Vista Home Premium. Which wouldnt matter anyway. If the BIOS doesnt see the memory, the OS wouldnt have anything to do with that. So how anyone could think it could be a problem with the OS is beyond me and flat out wrong. After explaining this and getting the team lead on the phone, they sent me out a new motherboard even though I was quite certain that wouldnt fix the problem, which it didnt. And now they are trying to tell me that it wont support 4GB of RAM after they cant think of anything else. The website says it does and that is why I bought the machine and the new memory, both of which I cannot return for a full refund.
Is there anyone else out there that ran into this? Anyone that has more than 2.5GB in their Lenovo 3000 J115? If yes, did you need to do anything special or did it just work.
Message Edited by akz28 on 02-22-2008 04:22 AM
Message Edited by akz28 on 02-22-2008 04:24 AM
Message Edited by akz28 on 02-22-2008 04:25 AM
Message Edited by akz28 on 02-22-2008 04:26 AM

Answer 1

The 3GB vs 4 GB limitation is actually a x86 issue, not operating system. A 32-bit system can only address 32 bits (4,096). There are a number of articles concerning this - Google 3GB vs 4 GB ram. Here is a link: http://www.codinghorror.com/blog/archives/000811.h​tml
The issue is basically a 32 Bit system can only address 4,096 of memory adressing. However in simple layman terms, the system must address all items on the bus like sound card, video, bios, pci bus, etc. (and the addressing of these items is like using memory).
Anyone familar with the old dos days remembers the software and memory managers we used to move the video, bios, etc above the 1 GB limitation, that way we had 640 KB Memory available for the applications.
Now several years later, we have hit the limit again, the 32-bit architectural now puts the addressing of items above the 3 GB level, leaving the lower 3 GB for memory use. So if 4 MB is installed, the 32-bit system addresses the computer components, then allocates what is left in the addressing range to the memory, thus why some systems with 4 GB do actually get 3.5 GB.
So on systems with 4 GB, with large memory video card and several other addressable items, it is percievable to only be able to use 3 GB. In fact, the recommendation with 32 Bit systems is to install 3 GB memory.
However, I do not know why the system wont recognize the installation in 3 GB mode only (have you installed only 3 GB total and see what it does?) My K100 system has 3 GB ram, (3) 1 GB sticks in 3 of the 4 memory slots. The system does recognize all 3 GB.
In fact, this addresses the reason Lenovo only put 3 GB in my system (I thought 3 GB was weird), because 4 GB would not all be addressed and the additional ram would be a waste of money.
Additional comments from users indicates that applications typically can only use the lower 2 GB anyway, thus leaving the last 1 GB for the OS (Vista). Unless you have applications that can use more Ram, the difficulty in getting the system to address the Ram differently wont gain you much.
And even a 64 Bit OS may not fix the issue, because some chipsets are only 32 Bit, thus addressing the components in the same method, which maybe why your system only see 2.5 GB at the bios level.
How much video memory you have? What do you have the allocation to the video memory set at in the bios?