Windows can only 4 GB of ram????? - Overclock.net

m11a1 · 02-16-07

A friend just told me that Windows XP can only recognize at the most of 4Gb of RAM, is this true?

Damage82 · 02-16-07

that's what I heard

Puckbandit35 · 02-16-07

if its 32bit .. i think it can really only reconize 3 gigs..64 bit reconizes 8 i believe...or maybe 4 not positive on that

speed_demon · 02-16-07

Quote:

32 bit addressing allows 32 bit version of windows to see 4,294,967,296 bytes of available memory.

The problem is in the implementation of PCI, it can only recognize 2^32, where the OS case be set to recognize above that. Typically, not always as there are a few exceptions, PCI devices will map their memory locations in the upper area's of available memory. I think, and this is my speculation, that it was one of those situations where hardware designers never thought home systems would have as much ram as we are now putting in them. In order to use that memory range for windows it needs to remap the the "used" area that the PCI devices are occupying. This is what the PAE, physical addressing extension does for your system.

It's kind of a simple explanation, I can't get too much more technical than that because it's beyond my level, but I know that's the rough idea.

here's a decent wiki entry on it as well, though, doesn't seem to mesh with mine, so I may be incorrect
http://en.wikipedia.org/wiki/32_bit

This kinda explains it. Edit: changed the link to a better one.

shajbot · 02-16-07

Yes, 4GB. And even though 4GB might be installed in system, Windows might not even recognize "full" 4GB.

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Windows can only 4 GB of ram?????

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