Does /Set IncreaseUserVa 3072 Fix 32bit apps with 4gb of memory?

Teki187 · 24 Apr 2008 at 20:30

Under Vista 32-bit:
1. Under Vista 32-bit (with at least 4GB memory installed regardless how much you see of it in windows) go START
2. Navigate to programs...etc until you see a black icon named "command prompt"
3. rightclick it and select: run as administrator. A big black box appears
4. In the big black box, type the following command: BCDEDIT /Set IncreaseUserVa 3072
5. Press enter to execute the command
6. reboot your computer

Apparently doing this in Vista 32bit enables you to use 4gb+.

Can anybody confirm?

RobH · 24 Apr 2008 at 20:58

It's been said before, you can't make use of 4GB on a 32-bit operating system, it's not a limit Microsoft put in place to make you buy x64, it's due to the architecture of the computer, 4GB cannot be fully addressed with 32-bits. So even if you can hack a 32-bit OS to see 4GB it won't be much use.

NathanE · 24 Apr 2008 at 21:12

32-bit = 4,294,967,296 bytes = 4GB.

However your physical memory is not the only "device" in the computer that needs mapping into the virtual memory address space. Many of your hardware devices do too. Your graphics card for instance will take however much memory is on it. 512MB card? Immediately you are down to 3.5GB available memory. Then your SATA controller (depending on how many ports) can take probably 16MB per port. Your network card. Your sound card. All of these devices take surprisingly large chunks of memory out of your VM address space. It is called DMA - direct memory access. It allows these devices to access memory directly without going via the processor, for performance.

Teki187 · 24 Apr 2008 at 21:19

NathanE said:
32-bit = 4,294,967,296 bytes = 4GB.

However your physical memory is not the only "device" in the computer that needs mapping into the virtual memory address space. Many of your hardware devices do too. Your graphics card for instance will take however much memory is on it. 512MB card? Immediately you are down to 3.5GB available memory. Then your SATA controller (depending on how many ports) can take probably 16MB per port. Your network card. Your sound card. All of these devices take surprisingly large chunks of memory out of your VM address space. It is called DMA - direct memory access. It allows these devices to access memory directly without going via the processor, for performance.

So whats the difference then in your case above between 32 and 64bit?

NathanE · 24 Apr 2008 at 21:23

64-bit = 18,446,744,073,709,551,616 bytes = 16,777,216 tera bytes

So basically you aren't going to care even if all your hardware eats 15 terabytes... you will still be able to slot in almost 2 TB of RAM