I 've had 8Gb out of 4*4Gb sticks ... so I try with some new sticks to upgrade to 4*8Gb but I still have only 16Gb available. (out of physical 32GB installed) whatever the setup is it is exactly half the installed ram.. There is no hardware issues (tested on other machines (tow different machines exactly)) bios = 32Gb detected Linux just sees 16GB ram dmidecode sees all of my 4 sticks # dmidecode -t 17 # dmidecode 3.1 Getting SMBIOS data from sysfs. SMBIOS 2.7 present. Handle 0x000E, DMI type 17, 34 bytes Memory Device Array Handle: 0x000D Error Information Handle: Not Provided Total Width: 64 bits Data Width: 64 bits Size: 8192 MB Form Factor: SODIMM Set: None Locator: DIMM0 Bank Locator: BANK 0 Type: DDR3 Type Detail: Synchronous Speed: 1600 MT/s Manufacturer: Unknown Serial Number: E09028A6 Asset Tag: Unknown Part Number: CT102464BF160B.C16 Rank: 2 Configured Clock Speed: 1600 MT/s Handle 0x000F, DMI type 17, 34 bytes Memory Device Array Handle: 0x000D Error Information Handle: Not Provided Total Width: 64 bits Data Width: 64 bits Size: 8192 MB Form Factor: SODIMM Set: None Locator: DIMM1 Bank Locator: BANK 1 Type: DDR3 Type Detail: Synchronous Speed: 1600 MT/s Manufacturer: Unknown Serial Number: E0902887 Asset Tag: Unknown Part Number: CT102464BF160B.C16 Rank: 2 Configured Clock Speed: 1600 MT/s Handle 0x0010, DMI type 17, 34 bytes Memory Device Array Handle: 0x000D Error Information Handle: Not Provided Total Width: 64 bits Data Width: 64 bits Size: 8192 MB Form Factor: SODIMM Set: None Locator: DIMM1 Bank Locator: BANK 2 Type: DDR3 Type Detail: Synchronous Speed: 1600 MT/s Manufacturer: Unknown Serial Number: E09027D2 Asset Tag: Unknown Part Number: CT102464BF160B.C16 Rank: 2 Configured Clock Speed: 1600 MT/s Handle 0x0011, DMI type 17, 34 bytes Memory Device Array Handle: 0x000D Error Information Handle: Not Provided Total Width: 64 bits Data Width: 64 bits Size: 8192 MB Form Factor: SODIMM Set: None Locator: DIMM3 Bank Locator: BANK 3 Type: DDR3 Type Detail: Synchronous Speed: 1600 MT/s Manufacturer: Unknown Serial Number: E0902882 Asset Tag: Unknown Part Number: CT102464BF160B.C16 Rank: 2 Configured Clock Speed: 1600 MT/s any idea why ? & how to activate all of it ? (currently runs fedora26/64bits also tested on debian/64bits) regards meminfo : bash-4.4$ cat /proc/meminfo MemTotal: 16307964 kB MemFree: 2589188 kB MemAvailable: 9856496 kB Buffers: 428964 kB Cached: 4553096 kB SwapCached: 132 kB Active: 7578520 kB Inactive: 4187932 kB Active(anon): 3926432 kB Inactive(anon): 745528 kB Active(file): 3652088 kB Inactive(file): 3442404 kB Unevictable: 24328 kB Mlocked: 24328 kB SwapTotal: 15569916 kB SwapFree: 15528188 kB Dirty: 3060 kB Writeback: 0 kB AnonPages: 6806540 kB Mapped: 1573064 kB Shmem: 363464 kB Slab: 645716 kB SReclaimable: 513068 kB SUnreclaim: 132648 kB KernelStack: 11552 kB PageTables: 55452 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 23723896 kB Committed_AS: 12692532 kB VmallocTotal: 34359738367 kB VmallocUsed: 0 kB VmallocChunk: 0 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB ShmemHugePages: 0 kB ShmemPmdMapped: 0 kB CmaTotal: 0 kB CmaFree: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 832256 kB DirectMap2M: 15822848 kB DirectMap1G: 1048576 kB free -m results on coherence with /proc/meminfo but dmidecode still confirm there are 4 distincts 8Gb ram sticks total used free shared buff/cache available Mem: 15920 4074 5169 204 6675 12038 Bios is so limited I can just manage boot order ... no options about memory or anything else... And Bios side it confirms 32Gb are present **Machine model : Aspire V3-772G The last bios is loaded : V1.15** that's all I can give usefull information dmesg analysis did not permit to get anything usefull . only a warning in loop about kvm/virsh setup : block like this one in loop no other informations at all [12341.196455] set_target_expiration: 30 callbacks suppressed [12341.196459] kvm: vcpu 0: requested 100012 ns lapic timer period limited to 500000 ns [12341.306246] kvm: vcpu 0: requested 292092 ns lapic timer period limited to 500000 ns [12341.704421] kvm: vcpu 0: requested 473064 ns lapic timer period limited to 500000 ns [12341.914420] kvm: vcpu 0: requested 468345 ns lapic timer period limited to 500000 ns [12341.924470] kvm: vcpu 0: requested 405938 ns lapic timer period limited to 500000 ns [12341.996356] kvm: vcpu 0: requested 100012 ns lapic timer period limited to 500000 ns [12342.096905] kvm: vcpu 0: requested 106350 ns lapic timer period limited to 500000 ns [12342.135880] kvm: vcpu 0: requested 424319 ns lapic timer period limited to 500000 ns [12342.406376] kvm: vcpu 0: requested 113630 ns lapic timer period limited to 500000 ns [12342.474998] kvm: vcpu 0: requested 271348 ns lapic timer period limited to 500000 ns So why linux (or any other OSs like BSD and so on) detects/activate only 16GB ?? how can I use the full ram ??