SPD information not available on C422 chipset, ECC Registered

[Ivo]

Hi all,
Hi Martin,

I want to report that there is no SPD information ( for each module- they are "emtpy" ) on Dell T5820 Precision workstation with Intel Xeon W-2155.
Installed memory is 4 x Samsung M393A2G40DB0-CPB , 16 GB each. Otherwise temperature sensors for each module are readable with hwinfo.
This is with the latest BIOS 2.8.0.

(Also SPD information is not available under linux 5.10.12 kernel ( with ee1004 module - which can get SPD from DDR4) . Using decode-dimms and i2cdetect. )

Thanks ,

Ivo

 

[Martin]

This is most likely due to Closed Loop Thermal Throttling (CLTT) - a mode which when activated in BIOS causes the IMC to periodically read DIMM temperatures (TSOD) via SMBus/I2C. This blocks all others from accessing the DIMM SPD information.

 

[Ivo]

here some logs

 

[Ivo]

This is most likely due to Closed Loop Thermal Throttling (CLTT) - a mode which when activated in BIOS causes the IMC to periodically read DIMM temperatures (TSOD) via SMBus/I2C. This blocks all others from accessing the DIMM SPD information.

Yes, seems to be you are right

 

[Martin]

Yes, I am TSOD polling is active.

 

[Ivo]

Just for information regarding this model workstation : there is no option in the BIOS to disable Thermal Sensor on DIMM.

 

[Martin]

It depends on BIOS whether it allows changing the memory thermal management.
If such an option is available then, then it's most likely called like "Memory Thermal Management Mode", OLTT/CLTT or similar.