0 Replies Latest reply: Apr 21, 2011 9:37 AM by nando4 RSS

Criteria for 36/64-bit 4500MHD PCI bar use in Win7?

nando4 Community Member
Currently Being Moderated

Hi,

 

I've got an unusual situation where a Dell Inspiron 1440 with 4500MHD/GM45 + T6600-2.2 CPU can setup 36-bit PCI BARs for use in Win7 as described at

 

http://forum.notebookreview.com/gaming-software-graphics-cards/418851-diy-vidock-experiences-35.html#post6056360

 

We can see in the link the 4500MHD 256MB prefectable BAR is located at the 12.25GB (36-bit) boundary. THis is great as it allows the 32-bit freed space to be used for an external desktop GPU which doesn't support 36-bit PCI BARs.

 

However, Dell Latitudes with P8xxx/T9xxx CPUs cannot do this, nor can a 2530P with a 4500MHD/GS45 + SL9400-1.86 CPU. In both cases Win7 moves the BARS back into 32-bit space, presumably because 36-bit is inaccessible. This is explained further at

 

http://forum.notebookreview.com/gaming-software-graphics-cards/418851-diy-vidock-experiences-227.html#post6949956

 

I'm wondering if it's the CPU that's preventing this from happening, or something else. PAE/DEP settings in the BCD don't fix the problem. If it's the CPU then,what MSR bit do I need to set to enable 36-bit PCI BAR usage in Win7? I hope the chipset isn't somehow limiting the PCI access to 32-bit only.

 

: confused :

 

Any help would be appreciated.

 

nando

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