RAM timings info slightly off

[A Penguin]

My RAM has 16-16-16-39 timings, but hardwareinfo says it's 16-16-16-40.

INFO:
RAM: 1x 8gb Gskill F4-2400C16S-8GRS DDR4-2400 SODIMM
HWiNFO version: 7.06-4500 64-bit (portable)

Debug file and report here https://www.mediafire.com/file/nyiqj8yli6z5kql/files.zip/file
(It wouldn't let me upload them here, not sure why)

 

[A Penguin]

It is correct here

 

[A Penguin]

wrong here

 

[A Penguin]

and here the top bit is wrong but the bottom bit is right

 

[Martin]

16-16-16-40 is the timing the module advertises as supported at 1200 MHz.
Actually the exact number is 32.5 / 0.833 = 39.0156, but the JEDEC standard says to round it to the next integer, so 40.

 

[A Penguin]

Not sure where you're getting the 40, anywhere I can find says 39. Why round up when it's so much closer to down though? Maybe the package/Gskill site rounded down?
Also, it's a little off for more than just that timing. Here's a lower one.
View attachment 6713

 

[Martin]

I explained above how and why the number is calculated.
Your other attachment seems to be missing.
I have done more research here and found an interesting thing. Earlier DDR4 specifications were using a 1% correction factor, but later ones changed this to 2.5%.
If software is using the 1% factor, then it gives 40. But applying 2.5% would result in 39. It's not common that specifications make a change that would have such an impact, but I will account for this change in the next build.