PAE (Physical Address Extension) will enable an application to grab the memory above the limit of a typical 32bit application, however the application needs to implement the Address Windows Extension (AWE) Application Programming Interface (API). There are only a few applications that are capable of this one of them is SQL Server. And there are other configuration options such as lock pages in memory must be enabled for the user/service account.

I don’t know that windows is automatically configured to use PAE on 32bit Windows platforms by default (maybe it is). But from my experience it’s always been something manually configured. But then again I only did Tech. Support M$ SQL Server for 10 years and left a little after the release of SQL 2005 SP1.

As for comments about negative impact using PAE, that’s true. Because to use the Extended memory the system acutally uses memory to map it. This has a two fold effect of reduced lower limit memory and increased processing just keeping up with the management of it. Adding larger amounts impacts more and more.

You could try using the /3Gb switch. In vista it’s called something else but the concept is the same. The option is known as “increaseuserva”. I wouldn’t recommend it if you have a lot of devices or you System does a lot of IO work. But… if you do use it keep under or ~3gb.

Here are some links that help exlpain a few things.
http://msdn.microsoft.com/en-us/library/aa906211.aspx
http://support.microsoft.com/kb/291988

I got 4Gb on my own pc just so I had dual channel ram running (4x 1Gb sticks). I don’t run the PAE switch or the /3gb equiv. in Windows Vista. For a server I would say go 64Bit anyway and why only 4gb of ram >:)

Vista reporting 4gb installed in computer properties as of SP1 is not the same thing as having 4gb available. Thats just a visual fix that came with SP1. Look at the performance tab of the task manager for the reality of whats available.

“I went up from 5.9 base score to 6.0 base now much of a Increase, but some”

Thats unbelievably impressive actually, considering wei scale currently only goes up to 5.9…..

This article is bogus btw, PAE does not work in this way at all, NOONE has this working anywhere, read ThetaSigmas post above as to why. Urban Legend indeed.

I currently have it set to /bcdedit set increaseuserva 2560 as wasnt sure.

Yes once Vista SP1 is installed your system will recognize the 4Gb of RAM. One thing that Microsoft did manage to fix. As I said One thing, though their are many fixes to come, heres the catch… Unless you are using any programs that require any large amount of memory, vista will still not utilize all 4Gb Of RAM. Though Just by updating my score. I went up from 5.9 base score to 6.0 base now much of a Increase, but some,

Vista Is still in its early years, I believe that atleast within another year we should should see a fairly good OS and even better within 2 to 3 years, As I will be patient with this OS I myself Am very curious to as how good this OS will be in the near future.

after installing sp1 both the system recognizes a complete 4 GB ram .before it recgnized only 3.5GB

they are both 32 bit

Correction of Mispellings:

c:\users\administrator>BCDEdit /set PAE forceenable

c:\users\administrator>
This Command Completed Succesfully