I'm getting some odd results using decode-dimms that I've been discussing on thinkpads.com. Perhaps someone here can give me an idea of how to understand this?
I have a collection of machines (two T500s, W500, T520) some of which have been presenting odd results in memtest86{,+}. The exact same known-good module is producing no errors, but a freeze in the test routines, specifically on "[Modulo 20, Random Pattern]". Despite this, they seem to run OSs without difficulty. In particular, no lockups.
So I was encouraged to check the SPD data. Running decode-dimms on each of those machines with that same module and booting from the same USB (Ubuntu 17.10 & i2c-tools v.3.1.2-3build2) produces contradictory results. Apparently correct in the case of the T520. Bad, but different, checksums and even different number of modules from the {T,W}500's. It is unlikely that the problem is all of these machines. In particular the W500 is basically unused.
It may not be a decode-dimms problem, but I thought someone might be able to give me a clue.
Thank in advance - /D
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T500* - This machine does not lock up on memtest86+
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Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/2-0050
Guessing DIMM is in bank 1
---=== SPD EEPROM Information ===---
EEPROM Checksum of bytes 0-62 Bad **Notice it's checking 63 bytes**
(found 0x40, calculated 0x93)
SPD Revision Invalid
Fundamental Memory type Unknown (0xff)
---=== Manufacturing Information ===---
Manufacturer Conexant (Rockwell)
Custom Manufacturer Data 00 4B CF 10 00 00 19 ("?K?????")
Manufacturing Location Code 0xB7
Part Number '
Manufacturing Date 0x0F00
Assembly Serial Number 0xB30A32B3
Number of SDRAM DIMMs detected and decoded: 1
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W500* - this machine does lock up on memtest86+
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Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/2-0050
Guessing DIMM is in bank 1
---=== SPD EEPROM Information ===---
EEPROM Checksum of bytes 0-62 Bad **Again, it's checking 63 bytes, but ...**
(found 0x50, calculated 0xDA)
SPD Revision Invalid
Fundamental Memory type Unknown (0xff)
---=== Manufacturing Information ===---
Manufacturer Invalid
Custom Manufacturer Data 24 00 4B CF 10 00 00 19 ("$?K?????")
Manufacturing Location Code 0x16
Part Number 1
Manufacturing Date 0x0F00
Assembly Serial Number 0xD10A32D1
Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/5-0050
Guessing DIMM is in bank 1
---=== SPD EEPROM Information ===---
EEPROM CRC of bytes 0-116 Bad **Here it's checking 117 bytes**
(found 0xFFFF, calculated 0x4FE6)
# of bytes written to SDRAM EEPROM 64
Total number of bytes in EEPROM 64
Fundamental Memory type Unknown (0xff)
---=== Manufacturing Information ===---
Manufacturer Undefined
Part Number Undefined
Number of SDRAM DIMMs detected and decoded: 2
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T520* - this machine tests perfectly on memtest86+
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Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/21-0050
Guessing DIMM is in bank 1
---=== SPD EEPROM Information ===---
EEPROM CRC of bytes 0-116 OK (0xD173) **Here it's also checking 117 bytes***
# of bytes written to SDRAM EEPROM 176
Total number of bytes in EEPROM 256
Fundamental Memory type DDR3 SDRAM
Module Type SO-DIMM
---=== Memory Characteristics ===---
Fine time base 2.500 ps
Medium time base 0.125 ns
Maximum module speed 1600 MHz (PC3-12800)
Size 4096 MB
Banks x Rows x Columns x Bits 8 x 15 x 10 x 64
Ranks 2
SDRAM Device Width 8 bits
Bus Width Extension 0 bits
tCL-tRCD-tRP-tRAS 11-11-11-28
Supported CAS Latencies (tCL) 11T, 10T, 9T, 8T, 7T, 6T, 5T
---=== Timing Parameters ===---
Minimum Write Recovery time (tWR) 15.000 ns
Minimum Row Active to Row Active Delay (tRRD) 6.000 ns
Minimum Active to Auto-Refresh Delay (tRC) 48.125 ns
Minimum Recovery Delay (tRFC) 160.000 ns
Minimum Write to Read CMD Delay (tWTR) 7.500 ns
Minimum Read to Pre-charge CMD Delay (tRTP) 7.500 ns
Minimum Four Activate Window Delay (tFAW) 30.000 ns
---=== Optional Features ===---
Operable voltages 1.5V
RZQ/6 supported? Yes
RZQ/7 supported? Yes
DLL-Off Mode supported? Yes
Operating temperature range 0-95 degrees C
Refresh Rate in extended temp range 2X
Auto Self-Refresh? No
On-Die Thermal Sensor readout? No
Partial Array Self-Refresh? No
Thermal Sensor Accuracy Not implemented
SDRAM Device Type Standard Monolithic
---=== Physical Characteristics ===---
Module Height (mm) 30
Module Thickness (mm) 2 front, 2 back
Module Width (mm) 67.6
Module Reference Card F
---=== Manufacturer Data ===---
Module Manufacturer SK Hynix (former Hyundai Electronics)
DRAM Manufacturer SK Hynix (former Hyundai Electronics)
Manufacturing Location Code 0x01
Manufacturing Date 2013-W32
Assembly Serial Number 0x1081FDE9
Part Number HMT351S6EFR8C-PB
Revision Code 0x4E30
Number of SDRAM DIMMs detected and decoded: 1
