4GBs of memory...

[hyp0dermik]

I am currently looking into building 2 new PCs for myself and my parents, and 4GBs of DDR2 1000Mhz is the same price is 2GB. However, after mucking around on the web I found a site that said Windows 32 bit only supports 4GB of memory, including graphics memory. The card is a 512MB 8800GT. Other sites seem to exclude this point. I realize that 64 bit supports more than 4GB, but have no wish to go through hell. Does anyone know the truth or have personal experiences?

[digip]

Intel boards with PAE turned on can use all of the 4 gig. Otherwise, its more like 3.6 gig or something like that.... and only shows up as somehting like 3 gig.(I think).

[Sparda]

http://sparda.hopto.org/hak5/36GB.png[/img]

Yes... when Ubutnu 8.04 comes around I may move to the 64bits, but even that has some compatibility issues (which are far fewer then any versions of Windows 64bit).

[cooper]

I don't believe the graphics card's memory is added to the on-board memory to create the total amount of memory that Windows can access. In fact, I'd be HIGHLY amazed if it did.

What instead happens is that the memory of your graphics card is mapped onto an equally sized chunk of memory on your system. Changes to the one carry over into the other (memory mapping).

Windows using it's standard 32-bit addresses can access up to 4 gigs of your regular memory. The graphics card doesn't come into play (but when the graphics card uses system memory, it might result in the memory being listed as less than what it really is, hence the note on the site). If you have more ram, you need PAE, which will add an extra level of indirection to your memory lookups, and thus slow the system down a bit. It will however allow you to address up to 64 gb of RAM. Note that not all chipsets support that much (4 gb and up)  memory.

[hyp0dermik]

The boards a Asus P5KC with an Intel P35 northbridge, ICH9(?) southbridge. Does PAE work on Intel boards only, or Intel chipsets as well?

[digip]

The boards a Asus P5KC with an Intel P35 northbridge, ICH9(?) southbridge. Does PAE work on Intel boards only, or Intel chipsets as well?

PAE was an Intel implemented feature after the Pentium Pro chips but other processors supposedly use it or similar functions as well. Also it is an issue not just limited to Windows XP.

http://en.wikipedia.org/wiki/Physical_Address_Extension

http://support.microsoft.com/kb/900524

@cooper - If I only have 2 gig of ram total and PAE is turned on, will it still slow me down?

It seems PAE is more than just for getting full use of your ram.

In Windows Server 2003 with SP1 and in Windows XP with SP2, the Data Execution Prevention (DEP) processor features require that the processor run in PAE mode. DEP is a set of hardware and software technologies. These technologies perform additional checks on memory to help prevent malicious code from running on a system.

Starting with Windows XP SP2, the 32-bit versions of Windows use one of the following hardware technologies to implement DEP: • The no-execute page-protection (NX) processor feature as defined by Advanced Micro Devices.

• The Execute Disable Bit (XD) feature as defined by Intel.

[JokerKing]

I have an AMD-based system, but in the BIOS it has an MTRR setting for "memory wrapping" so that 4GB or more of memory.  Not sure if this helps or if it's applicable, but there it is.

[cooper]

@cooper - If I only have 2 gig of ram total and PAE is turned on, will it still slow me down?

I would say 'yes' because the PAE way of doing things adds that extra level of indirection. Wether you _need_ PAE to get shit done doesn't change the way PAE itself works at the processor level.