*-PAE Mode-*
PAE is the second method supported to access memory above 4 GB; this
method has been widely implemented. PAE maps up to 64 GB of physical
memory into a 32-bit (4 GB) virtual address space using either 4-KB or
2-MB pages. The Page directories and the page tables are extended to 8
byte formats, allowing the extension of the base addresses of page
tables and page frames to 24 bits (from 20 bits). This is where the
extra four bits are introduced to complete the 36-bit physical address.
Windows supports PAE with 4-KB pages. PAE also supports a mode where
2-MB pages are supported. Many of the UNIX operating systems rely on the
2 MB-page mode. The address translation is done without the use of page
tables (the PDE supplies the page frame address directly).

I only have seen a few CAD applications successfully access PAE. Most
applications on the market can't use PAE properly. So for most users it
is a moot issue. You are still limited to physical RAM of 4GB with most
applications limited to 2GB per application. Applications like Photoshop
CS2 are paritally 64-bit and can access 6GB of RAM and a larger paging
file. It is very few applications that can use PAE. Personally, I rather
have 64-bit applications and more physical RAM instead being used in
Vista over using paging files that are 1000x slower access. As 64-bit
applications become available, it would be better to add RAM over paging
space.

It was $44 per GB for my 16GB of DDR667 RAM = $700.Benchmark Results
Combined Index : 24648 MB/s
Speed Factor : 42.2
2kB Blocks : 110697 MB/s
4kB Blocks : 120317 MB/s
8kB Blocks : 129715 MB/s
16kB Blocks : 133004 MB/s
32kB Blocks : 133339 MB/s
64kB Blocks : 119000 MB/s
128kB Blocks : 45663 MB/s
256kB Blocks : 45800 MB/s
512kB Blocks : 45807 MB/s
1MB Blocks : 45851 MB/s
4MB Blocks : 45300 MB/s
16MB Blocks : 15601 MB/s
64MB Blocks : 3160 MB/s
256MB Blocks : 3160 MB/s
1GB Blocks : 3160 MB/s
4GB Blocks : 3161 MB/s
Results Interpretation : Higher index values are better.

It is much faster than the $2200 SAS RAID controller and arrays.
RAID 1 array
Buffered Read : 1.01GB/s
Sequential Read : 119.73MB/s
Random Read : 128.25MB/s
Buffered Write : 679.29MB/s
Sequential Write : 31.91MB/s
Random Write : 31.21MB/s
Random Access Time : 1ms


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SCSIraidGURU

Michael A. McKenney
'www.SCSIraidGURU.com' (http://www.SCSIraidGURU.com)

Supermicro X7DWA-N server board
pair of Intel E5430 quad core 2.66 GHz Xeons
16GB DDR667
SAS RAID
eVGA 8800 GTS 640 MB video card