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
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.