What is the maximum memory (RAM) limit for 64-bit Windows 7 ?

This article is several months old, but I found it to be useful and informative.

By Windows Club | September 6th, 2009

Different Windows editions have had different upper maximum RAM limits. 64-bit Windows support different amounts of memory as a SKU-differentiating feature, with the low end being 512MB for Windows XP Starter to 128GB for Vista Ultimate and 192GB for Windows 7 Ultimate.


All 32-bit Windows client SKUs, however, including Windows Vista, Windows XP and Windows 2000 Professional, support a maximum of 4GB of physical memory. 4GB is the highest physical address accessible with the standard x86 memory management mode. Hardware Specifications for Windows 7 lays down the minimum memory (RAM) requirements.


So, while the maximum RAM limit for 32-bit Windows 7 editions is 4GB, when it comes to the 64-bit editions, the amount of memory that the OS can address depends on which edition you are running.


Here are the upper RAM limits for the different editions of Windows 7:


These limits are similar to those for Vista editions, except that Vista Enterprise and Vista Ultimate have had their upper limits raised from 128GB to 192GB.

SOURCE

One should also note there is hardware limits. Max memory per slot on the motherboard.

Unless I am badly wrong it would take a server type motherboard to enable memory over 24GB (6x4GB).

You ARE correct. I just thought is was an interesting article.

But then again, nearly all users don't need more than 6GB of RAM anyway.