I had this problem on my computer. Its Windows 32 bit did not recognise the 8GB ram that I had installed on it. After searching in the internet, I found that there is no technical reason why Windows 32 cannot read and address the full ram capacity that my computer has. The reason for the problem is that perhaps Microsoft did it intentionally to offer its variety of products with different prices.
The following link takes you to a 100% correct solution. I tried the patch on my computer and it worked. My computer is now recognising the full Ram capacity, which is 8GB. Its speed is now better than ever before.