Not able to read SPD

[zenmota]

When I select Read SPD (or something like that) from the main menu I get a SPD Not Detected on the 2 memory chips I have. They are G.Skill F56000J3238G32GX2-RS5K DDR5. The motherboard is ASUS ROG Maximus Z790 Hero. Have attached Screenshots and log files. Thanks....

[Simon (PassMark)]

Can you check that SPD writes disable is set to false in your BIOS:
https://www.memtest86.com/tech_ram-spd.html#ddr5-spd

[zenmota]

It is set to TRUE. If I set it to false and leave it there, will it hurt anything? What I mean is should I leave it on TRUE (except when running Memtest86) for security reasons? Thanks...

[David (PassMark)]

If you have malicious software on your machine and SPD writes are enabled and you are running as Admin and the malicious software has a Microsoft signed device driver in it that can read the SMBus and SPD data, then in theory it might be possible to rewrite the SPD data on the RAM sticks. Which could in theory leave the RAM sticks unusable (and thus the machine couldn't boot).

I'm not aware of any Virus that does this however. If you have malicious software on your machine, then it could also just wipe your hard disk, or do just about anything else. So leaving writes enabled doesn't really hurt security.
It is already game over once the malicious software gets installed.

Also SPD writes can be required to get RGB lighting enabled on RAM sticks.

Finally, in MemTest86 no actual writes are performed on the SPD, SMBus write operations are required to access the full 1024 SPD bytes. This is because only pages of 128 byte SPD data can accessed at once, and SPD Writes are performed to read all 8 pages. So we need to do a write to switch pages. (Bad, short sighted design of the SPD data storage area)

Background information.
SPD data
https://en.wikipedia.org/wiki/Serial_presence_detect

SMBus
https://en.wikipedia.org/wiki/System_Management_Bus

[zenmota]

Setting it to False fixed the problem. Probably just leave it set to True. I mean I shouldn't need to run Memtest86 on this computer everyday. Thanks for the quick reply and all the info.

[zenmota]

While setting the BIOS setting SPD writes disable to false allows Memtest86 to read the SPD, I noticed that when this is set to false and Memtest86 is running (testing the memory) where it shows the memory temperature it will have RAM Temp: N/A. If I set the BIOS setting SPD writes disable to True, while it may not be able to read the SPD when Memtest86 is running it will show the memory temperature. This is with Memtest86 10.5, not sure if this happened with earlier versions. Thanks

[keith]

We are looking into reading DDR5 SPD data without having to change the SPD write disable setting in BIOS.
Some tools (eg. CPU-Z) can do this already.