4 GB of RAM Only 2.99 GB usable?? Windows 7 32 bit

[ShadowShocks]

So, I was looking through my garage. Found my old PC that I forgot I left a stick of ram in and my current PC could use an extra GB so. I decided to take it and put it in my new PC and so I did. After I installed it I power my PC on and check my Computer Properties to see if it installed and it says this.
Installed memory (RAM): 4.00 GB (2.99 usable)
Why is it not using 4 GB? Please, help!

 

[vesp3r]

32bit system recognize max to 3GB ram
If you want it all to be used then you should check if your processor supports 64bit systems
Other than that your windows reserves 1GB RAM for itself.... Usable means thats what you CAN actually use and not whats being used

 

[girdwood]

Is it equipped with an onboard GPU, like an Intel GPU, or on board nvidia or ATI?

Onboard GPUs can come with up to 2 GB SHARED RAM, which means it reserves that smount of RAM from your current installed amount.

 

[jmsellars1]

It is likely that Windows or your integrated graphics is reserving some of it.

However I problem I have had in the past as well is a faulty RAM slot on the motherboard. I've had 8GB of RAM and Windows says 4GB usable then if I move the RAM to different slots it says ~8GB usable. That's another possibility.