Block clock issues

[Edkiefer]

I have a Asus P8Z77 Pro MB with 3570k, with default settings I noticed over a small period of time my block clock will show like 102mhz in max column.
This seems to happen after display goes to sleep (note this system has sleep disabled in power plan and hibernation disabled (C states enabled in bios still).

Now I did search around, and found if I uncheck periodic polling it is fine, but my understanding its not checking bus speed regularly.

Now compared to other app like CPU-Z, that has a known 99.9mhz showing for 100mhz bus, but it has no min/max saved values.
I also have Openhardware monitor and it seems that it doesn't poll the bus either (never seen anything other than 100, even if I OC to say 101 for test.

So my question, is this a known problem reading bus clock, that it reads wrong value, I have periodic polling unchecked which does seem to work but feels like a hack to me as it not monitoring bus speed.

 

[Martin]

Such a fluctuation is possible on some systems, but it's only a problem of the measurement method.
Unfortunately there's no 100% accurate method known for certain systems.

 

[Edkiefer]

Ok, thanks for info, I did also try Intel XTU utility and that was only one that seemed to work better, but it was fast test.
After letting system display go to sleep which seemed to trigger the variation, XTU shown only 100.2.
I don't think the system really did 102.5 as was shown, I think in the order of 0.5 would be more norm, but I have no way to tell as all tests are software based and i am not going to try an probe the bus with oscilloscope.

On positive note HWinfo64 does show Asus specific data fine >Dram v, CPU pll, etc, no issues with it, though I normally disable them after checking for every day use.
I also use HWinfo with MSI AB, which both work great if I need some data point on screen.
So I'll leave it with polling off, as I don't need bus clock really, I am not OC that bus.
Thanks again, great product.
Ed