Memory
DDR2 模組上的記憶體時鐘低於預期
我在 Dell Precision T7400 上執行了記憶體升級。官方使用者指南指出：
規格
記憶體類型：667 或 800 MHz 全緩衝 DDR2 SDRAM 全緩衝 DIMM (FBD)
最小記憶體：1 GB
最大記憶體：64 GB，帶可選記憶體轉接卡，32 GB 標準
我沒有使用記憶體提升板。我有 8 個 4GB 三星 800 MHz FB-DIMM DDR2（產品程式碼M395T5160CZ4-CF76）。記憶體正在工作，但時鐘錯誤：
$ 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-CF76dmesg MTRR 中出現一條可疑消息：
[ 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)為什麼我的記憶體可能會出現頻率不足，我可以解決這個問題嗎？我在 BIOS 中看不到任何相關的可修改設置。
T7400的戴爾規格表說：
800MHz 記憶體需要 1600MHz 前端匯流排至強處理器
MTRR 部分適用於 Linux 中的記憶體佈局，您應該考慮修復它，但它與記憶體時鐘速度無關。