[TUTORIAL] Enable Windows Vista 32bit to support more than 4GB of RAM

[CYBER WEESJE]

Many people claims that Vista is sucks because they can't support large physical memory such as 4GB and above. To be true, actually the issue is not caused by the Windows Vista itself however more to the 32-Bit Operating System nature.

Let me explains why a 32-Bit (x86 architecture) operating system does not able to support more than 4GB Ram.

Typical 32Bit after it was converted to binary, the maximum amount you can get from here is 32 numbers of 1. (11,11111,11111,11111,11111,11111,11111). If you take this number and convert to decimal you would get 4294967295. From here we can know that maximum amount we can have is 4294967295 B. In order to know the maximum amount in GB, do the following calculations :
4294967295/1024 = 4194303.9990234375 KB
4194303.9990234375/1024 = 4095.99999904632568359375 MB
4095.99999904632568359375 /1024 = 3.999999999068677425384521484375 GB

which round up to be 4GB.

In Windows Vista, approx 500MB would be used to memory-map other hardware. Hence it would only shown up 3.5GB of RAM if you had 4GB of RAM slotted into your DIMM slots.

To overcome this, usually people would suggest you to migrate to a x64 architecture which is a 64-Bit system. This push up the RAM support up to 16exabytes (I wonder how many people did really need such amount of ram). However not every computers are able to support 64bit or x64. There are also certain people depends on the 32bit system too.

Hence, in order to achieve memory higher than 4GB in a 32bit system, there is another way which currently used by Windows Server 2003. The keys lies in a features called PAE (Physical Address Extension) which is supported by most of the modern processor. A PAE enabled OS would have a 36bit memory space instead of 32bit. Hence use back the good old calculations, we would now have maximum of 64GB of RAM supports.

Alrite now we knows that PAE has such capabilities, and the next question that you might be asking is, how to enable it? Well for those who are familar with BCD (Boot Configurations Data) in Windows Vista, you would have an options to enable the PAE easily by follow the steps below :

Quote:
1. Click on the start menu, and type CMD.
2. Right click on the Command Prompt, and Run as Administrator.
3. Type "BCDEdit /set PAE forceenable" in the command prompt.


That's it. This should enable the PAE after machine was reboot.
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