Please explain SPD Not Detected

[DoctorDan]

Hello,
I have 2-32gb Crucial modules installed. The SPD Info says the first one is detected and it says the second is not detected.
What does that mean? Is the second module defective?

This is an ASUS MB and SPD Write Disable has been set to FALSE

Thank you

[David (PassMark)]

There are a bunch of different reasons the SPD data might not be available.

But check the obvious ones first.
1) Not connected: Is the RAM stick fully inserted in the slot?
2) Bad slot: If you install just the suspect stick by itself in several different RAM slots does it always fail and does the other stick always work?

[DoctorDan]

Thanks. I will check those things

[DoctorDan]

It looks like slot 4 on the MB is bad. What is the impact on operations if the SPD is not detected? I'm running Fedora 36 and have had 2 spontaneous reboots in the past week.

Thanks

[David (PassMark)]

SPD chip is connected to the CPU via the SMBus (which has a couple of wires running around the motherboard and going to each of the RAM slots).

Behaviour of missing SPD data will depend on the motherboard and the BIOS firmware. It might ignore the stick entirely or set the entire machine to run at some non optimal RAM clock speed, voltage and timings. Who knows......

The only thing that is sure is that it isn't good.

[DoctorDan]

I guessed not. I'll get on to ASUS. They will no doubt replace the board but this is the third ASUS MB that has failed in the past year. I may just abandon it and replace it with as Asrock as I have done with two of the ASUS. I'm accumulating quite a stock of supposedly good ASUS mb's that I have been unwilling to try out due to the effort of swapping boards/cpu's in and out.

Would the pro version of memtest86 tell me any more about this?

Thanks for your help

[David (PassMark)]

Would the pro version of memtest86 tell me any more about this?

Probably not.
If it really is an electrical fault, then it can't be fixed from software.

[DoctorDan]

More info and even more confused.
I've swapped in a new motherboard (different mfg) and rerun the spd info display. It still says that the SPD in slot 4 is not detected. I have swapped the 2 rams between slots 2 and 4 and get the same result.

Is this a bug/glitch in MemTest? CPU-Z did not have a problem reading the SPD data from any/all installed modules. So this has me really baffled.

Any thoughts?
Thanks

[David (PassMark)]

Bug in MemTest86 doesn't explain the spontaneous reboots in linux.

What version of Memtest86 you using?

Can you post a debug log.
https://www.memtest86.com/tech_debug-logs.html

[DoctorDan]

The version I have I downloaded on 11/11. The web site says it is version 10 build 1000.

I have more info. I have 2 machines. Both have Asrock Steel Legend motherboards. The one in question has a z590 chipset and and a 10th gen I9. The other one has a B550 chipset and a Ryzen 5600.
Both have ram in slots 2 and 4.
The AMD system detects SPD on both slots
The Intel can't find SPD on slot 4 with either the Asrock or the ASUS motherboards
I'm attaching both logs and a screenshot from the Intel box

[DoctorDan]

I found i2c-tools and ran the app that decodes the spd eeproms. The results are attached. It shows comparable output for both slots, suggesting that there is in fact no problem with slot 4.

Any thoughts?

[keith]

Thanks for the logs.

The issue seems to be related to the serial # of both modules being set to '00000000' which caused some confusion (which is a bit strange for commercial RAM).

We made a fix to handle this case. Can you give this build a try:

https://www.passmark.com/temp/memtes...-10.0.1006.zip

[DoctorDan]

Yes, both SPD's are now detected,
Thanks