DDR2模块上的内存时钟低于预期

我在Dell Precision T7400上执行了内存升级。 官方用户指南指出：

产品规格

内存types：667或800 MHz全缓冲DDR2 SDRAM全缓冲DIMM（FBD）
最小内存：1 GB
最大内存：64 GB（可选内存提升卡），32 GB标准

我不使用内存提升。 我有8 x 4GB三星800 MHz FB-DIMM DDR2（产品代码M395T5160CZ4-CF76 ）。 记忆在工作，但在错误的时钟：

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$ 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同意：

 $ 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 

一个可疑的讯息出现在dmesg MTRR：

 [ 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) 

为什么我的记忆会被低估，我能解决这个问题吗？ 我在BIOS中看不到任何相关的可修改设置。