Can you run less than 4GB on a 64 bit OS?

I've not tried with Windows 7, but XP64 used to run just fine with 2GB and any form of Linux or BSD will work fine with 1GB. There's nothing magic about 4GB (other than it's the most memory you can access with a 32-bit address) and, contrary to popular opinion, there are more advantages to 64-bit code than just memory.
 

imrul

Distinguished
Jun 22, 2007
446
0
18,810
the "64-bit" part communicates the potential amount of memory you can have (16 exabytes or 16 billion gigabytes).

when it says "32 bit" it means your potential is up to less than 4 gigabytes
 

verbalizer

Distinguished
yes, but you don't want too...
I'm lukewarm on 64-bit because I'm not convinced the average human will notice any performance benefit at 4GB or less of RAM.
It's more important to me that our old hardware and software works, which is does flawlessly on Win7 32-bit.
Besides, the only PC in our household that can take more than 2GB of RAM is my desktop, and I installed only 4GB ---
WAY more than enough for my needs but not enough to justify 64-bit.

http://zone.ni.com/devzone/cda/tut/p/id/5709
 

I'd agree with what you say when running 32-bit software, but 64-bit software can take advantage of several features of a 64-bit processor that should make them appreciably more efficient. For example, in 64-bit mode the processor has access to an additional 8 general-purpose registers; a good 64-bit compiler will take advantage of that and so produce more efficient programs by letting frequently accesed variables use these registers. That's just one example; there are others (including, of course, the ability to load data from memory 64-bits at a time, so twice as fast as in 32-bit mode) particularly when floating-point and multimedia registers are used.

So as more 64-bit programs become available 64-bit users will see significant improvements not just because of the ability to address more memory.
 

mrsubliminal

Honorable
Jun 5, 2012
1
0
10,510
I run a 6 core AMD Thuban processor on an older AM2+ motherboard with 4 GB DDR2. I use three monitors on the system: Two on a PCIE dual head graphics card with 1GB RAM, one on the native VGA graphics built into the motherboard.

My system memory is 4GB, and I use the system as a digital audio workstation. Recently, I upgraded to Adobe Audition CS6.

I recently switched to the 64 bit Windows 7 OS (actually dual booting both 32 and 64 bit). When running in 32 bit mode, I was constantly having to reclaim memory using Iolo System Mechanic, because when I had my music apps loaded, free memory would dip down to less than 512K. I was also getting some stuttering, and Audition CS6 was not loading the cores equally (i.e. it was pegging core 5 up to >95%, which would make the DAW stutter. Huge drop in performance from Audition 3.01.

Using 64 Bit Windows with Audition, Motu's Cuemix software, MIDI Ox, and a boatload of plugins, Audition loads the cores more evenly, and more importantly, I have 2GB free. Even using deep memory defragmentation on System Mechanic would not get me near to that.

The moral of the story is don't forget to include your video card ram in your ram count. My system has 5 GB ram including the video card, and the 64 bit OS has made a huge difference in performance and stability. In 32 bit Windows, the video ram eats into your 4GB limit, and even physical address extensions won't help you.