While I was researching a bit, I found this information in the Gigabyte GA-853-HD3 manual:
"* Due to a Windows 32-bit operating system limitation, when more than 4 GB of physical memory is installed, the actual memory size displayed will be less than the size of the physical memory installed."
I'm completely confused by this, since the motherboard supposedly supports the Intel Core i5-4570 CPU, which is a 64bit Haswell CPU. Can anyone shed some light on what the above quote means, and if I need to change the motherboard?
Operating systems come in 32-bit and 64-bit variants. That quote means that no matter how much memory you install, a 32-bit system will not be able to use more than 4GB. This is why you should always get a 64-bit copy of Windows.