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How to tell for sure if PAE (Physical Address Extensions) is enabled or not?
There is a SPECIFIC command I can use? I can read a registry value or something? (Windows 7 32 bits)

I have found this on Internet but it doesn't answer my question:

If your server has hot-add memory ability (ability to add more memory without shutting down the server !!) or data execution prevention (DEP) is enabled then PAE will be enabled automatically !!

It only reformulate the question as "does my Qosmio x505 laptop support hot-add memory?"

GoUkraineGo
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6 Answers6

17

To use the graphical user interface to determine whether PAE is enabled, follow these steps:

  1. Click Start, click Run, type wbemtest in the Open box, and then click OK.
  2. In the Windows Management Instrumentation Tester dialog box, click Connect.
  3. In the box at the top of the Connect dialog box, type root\cimv2, and then click Connect.
  4. Click #Enum Instances".
  5. In the Class Info dialog box, type Win32_OperatingSystem in the Enter superclass name box, and then click OK.
  6. In the Query Result dialog box, double-click the top item. Note this item starts with "Win32_OperatingSystem.Name=Microsoft..."
  7. In the Object editor dialog box, locate the PAEEnabled property in the Properties area and double-click on it.
  8. In the Property Editor dialog box, note the value in the Value box.
Indrek
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Victor Drobysh
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13

WMI will give you this via the command line util 'WMIC', for example:

C:\> wmic os get PAEEnabled
PAEEnabled
TRUE

C:\>

Or with Powershell:

PS> (Get-WmiObject win32_operatingsystem).PAEEnabled
Callie J
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3

How to tell for sure if PAE (Physical Address Extensions) is enabled or not?

On any modern Intel/AMD (x86/x64) system with hardware-level DEP, PAE is enabled out of the box on Windows XP (SP2?) and up, since it's required for the DEP feature to work.

"does my Qosmio x505 laptop support hot-add memory?"

No, it most assuredly does not.

Hot-add RAM is generally only found on high-end server hardware.

Edit:

According to MSDN Entry for PAE, it's enabled by default under certain (common) conditions:

Windows automatically enables PAE if DEP is enabled on a computer that supports hardware-enabled DEP, or if the computer is configured for hot-add memory devices in memory ranges beyond 4 GB. If the computer does not support hardware-enabled DEP or is not configured for hot-add memory devices in memory ranges beyond 4 GB, PAE must be explicitly enabled.

So, if the system is booted with PAE force-enabled or supports hardware DEP, PAE is on. That's every single system that's come with Vista or Windows 7 pre-installed, and a significant number of XP systems as well (late P4, Core Solo/Duo, Core 2 systems). The only caveat is if someone has gone out of their way to force disable it by editing the boot.ini file (for XP) or modify the BCD (for Vista/7).

As for how to see that it's enabled, I'm not sure. In XP, if you right click on My Computer and select Properties, the General tab will say Physical Address Extension at the bottom if PAE is enabled. 64-bit Win 7 systems don't seem to say, probably because PAE is always enabled on such systems. 32-bit Win 7 may say something similar in the System Control Panel, but until I can check my home laptop, I can't tell you for sure -- it's the only 32-bit Win 7 system I have access to, all my others are 64-bit.

There doesn't seem to be any registry entry that tells whether or not it's on.

Ultimately, the point is that it's safe to assume it's on unless you have a good reason to believe it's not. If you're writing code that depends on it, use the IsProcessorFeaturePresent function, that's what it's there for.

afrazier
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3

There is a registry setting that will tell you whether Physical Address Extension (PAE) is enabled.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PhysicalAddressExtension

If it is set to 1, then the kernel with PAE support was loaded at startup.

Alistair McMillan
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0

you can simply run command prompt as administrator and execute "bcdedit" if at all enabled there will be an entry under the operating system parameters as PaeForceEnabled = true

mayank gupta
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A laptop almost certainly does not support hot-add memory. That feature only exists on certain high-end servers.

Windows XP SP2 and later versions of the client OS do not support more than 4GB of memory in 32 bit mode, even with PAE enabled because of driver compatibility issues. PAE is only used so the OS can access the NX bit.

See http://msdn.microsoft.com/en-us/windows/hardware/gg487512

If your CPU supports the NX bit, unless you are booting with the /NOPAE flag the kernel is probably using PAE for hardware DEP support.

Chris Smith
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