Memory upgrade from 4GB to 6GB..not working

First of all, thank you for letting me be a part of this forum. At my job, all we have are Lenovo's. From the T41, 42, 42P, 43, 60, 400 and the X41.

I just upgraded a T-400 from 4GB to 6GB RAM. It had 2 2GB sticks in it. I swapped one of the 2GB sticks for a 4GB stick. Tried it in both slots. The laptop is still only displaying 2.96GB of RAM.

Can anybody tell me why?

 

The "2.96" is the dead giveaway. You're running a 32-bit operating system, and the limitation of 32 bits of address space is 2^32, or 4294967296 bytes (ie, 4GB) The reason you're seeing 2.96Gb available is due to the way that 32-bit OSes load drivers and do memory-mapped IO for devices that have their own ram.

The biggest thief of your available ram under a 32-bit OS is the memory mapped region for your video card (or cards, if you have switchable graphics.) While a video card with it's own dedicated ram isn't physically USING any of your system ram, the fact that that video memory must be addressable by the OS means that it must appear to be under the 4Gb limit. Thus, if you have a 1Gb video card installed, that 1GB will be "mapped" into the highest region under 4GB -- there's 1GB of your system ram that's no longer visible to the OS.

Other notables would be the sound card, the two network cards, and whatever other PCI or PCI-E devices you have on your system. In order to see anything more than what you're getting, you'll have to switch to a 64-bit OS.

 

Thank you!