RAM LIMIT https://en.wikipedia.org/wiki/RAM_limit MOTHERBOARD ----------- 6 TB RAM motherboard https://www.supermicro.com/products/motherboard/Xeon/C600/X10QRH_.cfm price: ~1300 USD https://www.ebay.com/itm/NEW-SuperMicro-X10QRH-Motherboard-FULL-MFR-WARRANTY-/361378830758 Motherboard matrix https://www.supermicro.com/ResourceApps/MB_matrix.aspx MS Windows ---------- Memory Limits for Windows and Windows Server Releases https://msdn.microsoft.com/en-us/library/windows/desktop/aa366778(v=vs.85).aspx macOS ----- https://everymac.com/actual-maximum-mac-ram/ iMac memory specifications https://support.apple.com/en-us/HT205040 GNU/LINUX --------- https://www.quora.com/What-is-the-most-RAM-a-computer-has-ever-had https://askubuntu.com/questions/142043/whats-the-maximum-amount-of-ram-i-can-use-on-an-specific-hardware https://unix.stackexchange.com/questions/116640/what-is-maximum-ram-supportable-by-linux https://access.redhat.com/articles/rhel-limits https://askubuntu.com/questions/557701/what-is-the-maximum-ram-supported-by-the-desktop-and-server-editions https://en.wikibooks.org/wiki/The_Linux_Kernel/Memory https://help.ubuntu.com/community/32bit_and_64bit#Memory A 32-bit computer has a word size of 32 bits, this limits the memory theoretically to 4GB. This barrier has been extended through the use of 'Physical Address Extension' (or PAE) which increases the limit to 64GB although the memory access above 4GB will be slightly slower. 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. Linux: https://www.kernel.org/doc/Documentation/x86/x86_64/mm.txt Virtual memory map with 4 level page tables: 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm 2^47 bytes = = 128TiB = ~140 TB # # # kernel boot parameters https://wiki.ubuntu.com/Kernel/KernelBootParameters GRUB_CMDLINE_LINUX_DEFAULT="quiet splash mem=1G" mem=nn[KMG] # # # Maximum supported RAM in Linux: https://www.ostechnix.com/how-to-find-out-maximum-supported-ram-in-linux/ sudo apt-get update && sudo apt-get install dmidecode && sudo apt-get clean dmidecode -t 16 #max supported # dmidecode 3.0 Getting SMBIOS data from sysfs. SMBIOS 2.4 present. Handle 0x0006, DMI type 16, 15 bytes Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: None Maximum Capacity: 8 GB Error Information Handle: Not Provided Number Of Devices: 2 dmidecode -t 17 #currently installed # dmidecode 3.0 Getting SMBIOS data from sysfs. SMBIOS 2.4 present. Handle 0x0008, DMI type 17, 27 bytes Memory Device Array Handle: 0x0006 Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: 4096 MB Form Factor: SODIMM Set: None Locator: DIMM0 Bank Locator: BANK 0 Type: DDR3 Type Detail: Synchronous Speed: 1600 MHz Manufacturer: 0x802C Serial Number: 0x32958DAE Asset Tag: Unknown Part Number: 0x384B54463531323634485A2D314736453220 Handle 0x000A, DMI type 17, 27 bytes Memory Device Array Handle: 0x0006 Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: 4096 MB Form Factor: SODIMM Set: None Locator: DIMM0 Bank Locator: BANK 1 Type: DDR3 Type Detail: Synchronous Speed: 1600 MHz Manufacturer: 0x802C Serial Number: 0x32958DAD Asset Tag: Unknown Part Number: 0x384B54463531323634485A2D314736453220