Частота памяти на модулях DDR2 ниже ожидаемой

Я выполнил обновление памяти на Dell Precision T7400. В официальном руководстве пользователя говорится:

Характеристики

Тип памяти: модули DIMM (FBD) DDR2 SDRAM с полной буферизацией на 667 или 800 МГц
Минимальная память: 1 ГБ
Максимальный объем памяти: 64 ГБ с дополнительными переходными картами памяти, 32 ГБ в стандартной комплектации

Переходники памяти не использую. У меня 8 x 4 ГБ Samsung 800 МГц FB-DIMM DDR2 (код продукта M395T5160CZ4-CF76). Память работает, но не в те часы:

$ sudo lshw -C memory | grep FB-DIMM
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)
          description: FB-DIMM DDR2 FB-DIMM Synchronous 667 MHz (1.5 ns)

dmidecode соглашается:

$ sudo dmidecode -t memory
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.5 present.

Handle 0x1000, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: Multi-bit ECC
    Maximum Capacity: 64 GB
    Error Information Handle: Not Provided
    Number Of Devices: 8

Handle 0x1100, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 1        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 53496E32
    Asset Tag: 010829
    Part Number: M395T5160CZ4-CF76 

Handle 0x1101, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 2        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 052048F7
    Asset Tag: 010812
    Part Number: M395T5160CZ4-CF76 

Handle 0x1102, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 3        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 052048EF
    Asset Tag: 010812
    Part Number: M395T5160CZ4-CF76 

Handle 0x1103, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 4        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 051FD1B0
    Asset Tag: 010811
    Part Number: M395T5160CZ4-CF76 

Handle 0x1104, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 5        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 050BD2E7
    Asset Tag: 010828
    Part Number: M395T5160CZ4-CF76 

Handle 0x1105, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 6        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 060BB367
    Asset Tag: 010828
    Part Number: M395T5160CZ4-CF76 

Handle 0x1106, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 7        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 060BB350
    Asset Tag: 010828
    Part Number: M395T5160CZ4-CF76 

Handle 0x1107, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x1000
    Error Information Handle: No Error
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: FB-DIMM
    Set: None
    Locator: DIMM 8        
    Bank Locator: Not Specified
    Type: DDR2 FB-DIMM
    Type Detail: Synchronous
    Speed: 667 MHz
    Manufacturer: 80CE7FB380CE
    Serial Number: 0529DA3A
    Asset Tag: 010825
    Part Number: M395T5160CZ4-CF76

В dmesg MTRR появляется одно подозрительное сообщение:

[    0.000000] DMI: Dell Inc. Precision WorkStation T7400  /0RW199, BIOS A11 04/30/2012
[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[    0.000000] e820: last_pfn = 0x830000 max_arch_pfn = 0x400000000
[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000]   00000-9FFFF write-back
[    0.000000]   A0000-BFFFF uncachable
[    0.000000]   C0000-DBFFF write-protect
[    0.000000]   DC000-EFFFF uncachable
[    0.000000]   F0000-FFFFF write-protect
[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 0000000000 mask 2000000000 write-back
[    0.000000]   1 base 00CFF00000 mask 3FFFF00000 uncachable
[    0.000000]   2 base 00D0000000 mask 3FF0000000 uncachable
[    0.000000]   3 base 00E0000000 mask 3FE0000000 uncachable
[    0.000000]   4 base 1FF0000000 mask 3FF0000000 uncachable
[    0.000000]   5 disabled
[    0.000000]   6 disabled
[    0.000000] x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- WT  
[    0.000000] total RAM covered: 130047M
... a bunch of gran_size / lose cover RAM ...
[    0.000000] mtrr_cleanup: can not find optimal value
[    0.000000] please specify mtrr_gran_size/mtrr_chunk_size
...
[    0.000000] Memory: 32900928K/33552024K available (8852K kernel code, 1441K rwdata, 3828K rodata, 1556K init, 1296K bss, 651096K reserved, 0K cma-reserved)

Почему моя память может быть недостаточно синхронизирована, и можно ли это исправить? Я не вижу в BIOS соответствующих изменяемых настроек.

memory frequency

В Спецификация Dell для T7400 Говорит, что:

Память 800 МГц требует процессоров Xeon с фронтальной шиной 1600 МГц

Часть MTRR применяется к разметке памяти в Linux, и вы должны исправить это, но это не имеет отношения к тактовой частоте памяти.