Vista 32/64 3GB to 4GB to 2GB Ram PAE

  Funkadelic5 11:22 11 Jul 2007

I realise there has already been discussions on this topic. However this is a slightly different query.

I have an Asus board (Intel P965 chipset) that supports memory remapping. I have 4 x 1GB of corsair ram. I'm dual booting Vista Ultimate 32 and 64 bit versions.

In the 32 bit OS I was only seeing 3GB and know why (see links below). In the 64 bit I was also only seeing 3GB ram until I enabled memory remapping and now I see all 4GB.

Question is - Why does enabling memory remap in the BIOS mean the 32 bit Vista OS now only shows 2GB?

I also understand that enabling PAE can affect performance so I've removed it from BCD in both the 32 and 64 bit versions - either way it makes no difference to the above situation!

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  Funkadelic5 17:35 13 Jul 2007

Explanation for the above issue - may help some people! I've spoken to Microsoft about this (have a technical support agreement through my company) and they've spent this week looking at this issue. A senior tech engineer has said that this occurs on some boards because the BIOS Memory Remap, remaps the entire top 2GB of physical ram above the 4GB physical boundary.

This is ok for Vista x64 as it will find and use all 4 GB but 32-bit Vista won't find or use it and will only have the bottom 2GB of physical memory that it can use.

Unless the vendor (Asus in this case) changes the memory remap architecture, there is nothing that can be done about this.

Additionally the MS engineer says it will never be possible to get the full 4GB in Vista 32-bit. The best one can get is 3.xGB in the 'non-remapped' mode.

This is from the guys that wrote the MS KB doc 929605 click here

They are looking into why MS KB doc 929580 contradicts this, click here looks like a rogue doc - PAE makes no difference (for me at least) on the above points.

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