• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

The 32-bit/64-bit/2GB Per App/Not really 4GB RAM Limit Thing

L

locutus

New Member
Joined
May 24, 2008
Messages
8 (0.00/day)
I'm trying to get a handle on the 32-bit/64-bit/2GB Per App/Not really 4GB RAM limit thing. Nice title huh? :)

A 32-bit app is limited to 2GB in Win XP32 unless you use the /3GB /userva switches in the boot.ini file and the app was compiled with the /largeaddressaware switch. Then the app can use close to 3GB. This I'm sure is right because I found it on so many sites.

A 32-bit app is limited to 2GB in Win XP64 (because XP64 is emulating XP32), unless you use the /3GB /userva switches in the boot.ini file and the app was compiled with the /largeaddressaware switch. Then the app can use 4GB. This I'm not sure about. According to one site I found, the app would have access to up to 4GB, but never more than 4GB. Is this right?

If XP32 made use of PAE the way it was intended we would have access to 64GB (although each app would still be limited to 2GB), but XP sets the limit at 4GB even though PAE is enabled.
 
Yeah nice title lol

Your right on the memory usage. But using switch in xp64 won't always work. There not many 64-app out there anyway. The heaviest program I use is Adobe CS3, which is only a 32-bit app. But works awhole lot better x64 world. But in till CS4 comes out, I'm stuck with just using 2gb out of the 6gb that I have in my rig now. Even if you use a patch or edit the boot.inf, that's really only going effect windows itself.
 
CrackerJack said:
But using switch in xp64 won't always work. There not many 64-app out there anyway.
Click to expand...

Do you mean using the switch with 64-bit apps? I wasn't talking about because with 64-bit apps you don't need the switch.

CrackerJack said:
The heaviest program I use is Adobe CS3, which is only a 32-bit app. But works awhole lot better x64 world. But in till CS4 comes out, I'm stuck with just using 2gb out of the 6gb that I have in my rig now. Even if you use a patch or edit the boot.inf, that's really only going effect windows itself.
Click to expand...

So you have 6GB in your system and Adobe CS3 works better in X64 than in XP32? That's weird because when you run it, X64 should be running CS3 within an emulation of XP32. That's what MS calls WOW64. That means it should be limited to 2GB just the way it is in XP32.
 
So you have 6GB in your system and Adobe CS3 works better in X64 than in XP32? That's weird because when you run it, X64 should be running CS3 within an emulation of XP32. That's what MS calls WOW64. That means it should be limited to 2GB just the way it is in XP32.
Click to expand...

It's just more responsive than x32.
 
I believe it, I've heard some places that the x86 emulation in vista is better than having a x86 OS in the first place.
 
Well i've tested: XP Home SP2, XP Pro SP2 x64, Vista x86, Vista x64. Out of all these, Vista x64 runs 10 times better. More stable and responsive.
 
Adobe KB said:
When you run Photoshop CS2 on a computer with a 64-bit processor (such as a G5, Intel Xeon processor with EM64T, AMD Athlon 64, or Opteron processor), and running a 64-bit version of the operating system (Mac OS v10.3 or higher, Windows XP Professional x64 Edition), that has 4 GB or more of RAM, Photoshop will use 3 GB for it's image data. You can see the actual amount of RAM Photoshop can use in the Maximum Used By Photoshop number when you set the Maximum Used by Photoshop slider in the Memory & Image Cache preference to 100%. The RAM above the 100% used by Photoshop, which is from approximately 3 GB to 3.7 GB, can be used directly by Photoshop plug-ins (some plug-ins need large chunks of contiguous RAM), filters, actions, etc. If you have more than 4 GB (to 6 GB (Windows) or 8 GB (Mac OS)), the RAM above 4 GB is used by the operating system as a cache for the Photoshop scratch disk data. Data that previously was written directly to the hard disk by Photoshop, is now cached in this high RAM before being written to the hard disk by the operating system. If you are working with files large enough to take advantage of these extra 2 GB of RAM, the RAM cache can speed performance of Photoshop.
Click to expand...

Took a high res poster-sized image with multiple layers, but I got memory usage over 2GB with both CS2 and CS3 :)
 
Jizzler said:
Took a high res poster-sized image with multiple layers, but I got memory usage over 2GB with both CS2 and CS3 :)
Click to expand...

Could that be because the image is eating 2gb of ram and then the amount that CS takes, or is it just the image?
 
CrackerJack said:
Well i've tested: XP Home SP2, XP Pro SP2 x64, Vista x86, Vista x64. Out of all these, Vista x64 runs 10 times better. More stable and responsive.
Click to expand...

Do you agree that XP32 is faster than Vista32? I just read an article in PCWorld that says Vista is slower than XP Pro. Even with SP1 which is supposed to speed Vista up, it's still slower than XP Pro. That's all 32-bit. They didn't measure 64-bit OSs.

Vista64 is much faster than XP64? How did you test them? Did you compare the performance in any games? I've heard Vista is very bloated.
 
locutus said:
Do you agree that XP32 is faster than Vista32? I just read an article in PCWorld that says Vista is slower than XP Pro. Even with SP1 which is supposed to speed Vista up, it's still slower than XP Pro. That's all 32-bit. They didn't measure 64-bit OSs.

Vista64 is much faster than XP64? How did you test them? Did you compare the performance in any games? I've heard Vista is very bloated.
Click to expand...

XP64 better used with games and benchmarks. But I was just saying CS3 and few other heavy programs run better on Vista x64.
 
You must log in or register to reply here.
Back
Top