I have a server machine with 6GB of RAM, with Win2K Advanced Server and SQL2K EE. I have to use /3GB and /PAE switches in the boot.ini file of the OS in order to take full advantage of the physical RAM. From SQL server I have to enable AWE in order to address this much RAM. Now according to Microsoft, with this much RAM, OS keeps for itself 2GB RAM, and the rest then is available for the application. With the help of /3GB switch, OS releases 1GB RAM out of its 2GB for the applications. So according to this theory, with my settings, I should have 5GB of RAM available (out of total 6GB physical RAM). But while enabling AWE, if I set the "max server memory" to 5.5GB, it is allocated to the Server leaving only 0.5GB for the OS. Can any body explain why is this contradiction??? I know that even Microsoft says that if we won't set the max server memory while enabling the AWE, AWE then will take all the available memory leaving behind only 128MB for the OS. This is a complete contradiction to the statements which Microsfot gives while explaining /3GB and /PAE switches.