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Posted: Thu Mar 17, 2011 5:14 am
by BitMask
PAE is not going to help you. The 3/4Gb limit is something that Microsoft impose on their OS which will make the Server OS more attractive. PAE is supported from most CPUs and motherboards/BIOS srom PIII and Athlon CPUs and later, but the MS Windows (non server versions) limit the memory usage.

But stick with 32bit for now. It works much easier and you will not feel the loss of that 400Mb RAM (compared to the driver/app pain of 64bit)

Posted: Thu Mar 17, 2011 5:23 am
by streu
Gavan wrote:Something to remember about a 64-bit Windows OS is that it uses 1.5 times the amount of memory to run a 32-bit app on a 64-bit platform. (and 90% of software is still 32-bit) This means you will get 2.5 GB worth of 32-bit apps running while using 3.75 gig memory on a 64-bit OS. (So one should have 6 GB of memory installed on a 64-bit machine to get 4 GB of 32-bit apps to run)
Any source for this claim? I don't see why a 64-bit OS would use more memory to run a 32-bit app than a 32-bit OS.

I know of two effects.
  • a 64-bit app uses more memory than the same app as 32-bit version because it has to store those 64 bits somewhere.
  • a 32-bit app will use 32-bit DLLs, while a 64-bit app will use 64-bit DLLs. That is, you'll have two copies of kernel32.dll loaded. But all 32-bit apps will share the 32-bit DLLs, and all 64-bit apps wil share the 64-bit DLLs.
But then, we are talking about VGAP here. PCC2 is so far the fattest VGAP application I've seen with its 4 MB .exe file, and I've never seen it need more then 15 megs with all images loaded. So how many copies of it do you want to start? :-)


Posted: Thu Mar 17, 2011 4:54 pm
by Gavan

1. MS says so
2. Citrix say so
3. I say so :D

I also did not believe this to be the case (nor did our client) so I had setup and prove it one way or the other and it is the case.

If you are interested I will write up a post with what we did, how we did it and what we found.

Posted: Thu Mar 17, 2011 5:04 pm
by Havok
How about just an online reference somewhere you can provide a link to. I'd like to read it myself. Thanks.

Posted: Fri Mar 18, 2011 8:31 pm
by Gavan
Here is one of the articles I have found. Not quite the Citrix one I was looking for nor is this the same way we did our testing but....

This is the conclusion page. ... bility.htm

And here is one about memory use for 32 bit vs 64 bit office. ... ervers.htm

Posted: Sat Mar 19, 2011 6:17 am
by streu
Gavan wrote:And here is one about memory use for 32 bit vs 64 bit office. ... ervers.htm
This one carefully avoids saying whether they're running 64-bit Office or 32-bit Office on their 64-bit OS. And, of course, 64-bit Office uses more resources than 32-bit Office, because it has to store the 64 bits somewhere.

I am not aware of any 64-bit Windows VGAP utility (there is a 64-bit version of PHost for Linux, though), so at least you won't be paying for that :-)