Mark Harrison
Posts: 3775
Nickname: mharrison
Registered: Dec, 2003
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Mark Harrison is Microsoft UK Systems Engineer focussing on .NET eBiz and Portals
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Dell M65 laptop 4Gb RAM
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Posted: Apr 27, 2006 6:05 PM
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Original Post: Dell M65 laptop 4Gb RAM
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Take care if you are in the market for a new laptop and considering 4Gb RAM.
So you pay a really huge premium (compared with 2Gb RAM) to get 4Gb of RAM ... and so how much memory do you expect the BIOS to make available to the OS. For a Dell M65 the answer is just 3.071Gb.
Response from Dell ...
The processor only has 32 address lines, limiting it to an addressing map of 4 gigabytes.
The chipset, PCI devices, PCI express region, and video cards use some of this map, and the BIOS correctly reports this range as unavailable to the operating system. If the user installs 4 GB of physical memory, then the processor has no way to address the memory that overlaps with these regions, already in use. The chipset directs memory access to the appropriate device rather than sending it to random access memory (RAM).
On Dell's new line of desktops, PCI express uses 500 megabytes (MB) in the map; integrated video takes 256 MB right below PCI express, leaving 3.25 GB of memory available to the operating system via RAM. In some cases, less RAM is available depending on what other add-in cards are installed.
Therefore there is no hardware or software fault with the system. This is working as designed.
Read: Dell M65 laptop 4Gb RAM
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