Installed Memory (Usable Memory)

Just as the topic looks, that's what I'm having an issue about right now. Now, lets begin by laying some different things out on the line. 1) I used search, 2) I used Google, 3) I even tested this on different machines (will explain below), and 4) I put this in the right forum... I hope..

Ok, I work in an office and I got an agent to come to me to help them install Java. Knowing he ran Windows 7 - Home Premium, I checked the System menu for what version OS he was running. I noticed 64bit, but couldn't help to notice that he had 3GB installed (2.75 being used)... Right away this through up a red flag because I thought that Home Premium 64bit was able to fully use every bit of installed memory up to 16GB. Acer is the manufacturer of the laptop, so I don't know if they might have something messed up in the BIOS or if it is simply because he got it about a week after Windows 7 was released.

The reason that I am fearing this is because I have a custom built desktop that is currently running 4GB (3.25 usable) of the Windows 7 RC Ultimate 32bit, so I know that I'm only going to get about that much out of my RAM. However; because it is soon time to reformat, I have a Windows 7 Home Premium 64bit CD + Key waiting to be used, and another 4GB of memory to be installed. I don't want to have an issue when reinstalling that I'm going to be missing any bit of RAM being used either just because I'm using Home Premium or any other reason.

Hello Joshgt2, and welcome to the forums :)

Theoretically 64bit can address 128GB of RAm , although Motherboards typically do not support such amounts yet.

Certain chipsets (Such as AMD) using built in graphics, will use a certain amount of RAM dedicated to graphics only.
(naturally it pulls this dedicated graphics memory from you installed RAM)

So if it is set dedicate say, 512Mb in the bios, and you have 4GB of RAM installed...

In Windows you would see something like 4Gb installed (3.5 useable)

By the same token, if you have 8GB installed, it would show 8GB installed (7.5 useable)

If you install a actual graphics card, and disable the onboard, you will gain full use of your RAM again, As a graphics card has its very own memory onboard.

hope this answers your question :)

That's all I needed to know! I had seen from other places that it MIGHT take into effect things that are running on the board, but I wasn't sure. I know that his system was using simple build in graphics and my own laptop has an actual card to do the work instead. Thanks again for the wonderful response.