What is the maximum RAM supported by the desktop and server editions?

I have just downloaded "ubuntu-14.04.1-desktop-amd64.iso" and "ubuntu-14.04.1-server-amd64.iso" through "".

Please can someone confirm the maximum RAM that is supported.

According to many sites, Maximum RAM supported by the OS

ubuntu-14.04.1-desktop : " 2^64 bytes " -- Kindly confirm

ubuntu-14.04.1-server : " 2^64 bytes " -- Kindly confirm

2 Answers

Maximum RAM supported by Ubuntu:

• Ubuntu 32-bit + PAE (Physical Address Extension) - 64GB RAM although the memory access above 4GB will be slightly slower. PAE is now the standard for 32-bit Ubuntu, so there is no need for enabling it.

• Ubuntu 64-bit - A 64-bit computer will be able to address up to 16.8 million TB (16 exabytes) although constraints are in place that limit this to around 1TB.

_{Reference: Ubuntu Documentation: 32-bit and 64-bit Community Help Wiki}

First, the only difference between server and desktop is what packages are installed by default; both run the same kernel. The maximum amount of memory supported on both is the maximum amount your hardware supports. The max for amd64 cpus is 2^48 bytes ( the architecture defines that the higher order bits are reserved ), but motherboards invariably have a lower limit they impose.