Strange CPU clock variances

Today I got bored and I stressed tested my Phenom II 955 with OCCT (it's avg max core temp is 62.5c but since AMD max temps for Phenoms are rated by the CPU sensor that's several degrees lower than core I'm safe although a bit hot.)

I noticed that both the CPU clock and FSB increased slightly, something that I have never seen before when I've stress tested it, it went up to 3.209 Ghz (3.200 Ghz is normal) at times, the FSB rose proportionately.

I know the variance is only around half a percent or so but was wondering if it's anything to be concerned about. I don't know what is the margin of error for CPU clock readings, so it could simply be just an off reading.

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Comments

exampasser

I've looked online and I haven't found anything so far.

tiersten

Its normal. The clock generator on your motherboard and CPU will vary slightly due to temperature and manufacturing differences. As the clock multiplier in CPUs now is high along with a high speed clock, you're noticing the variances more than before.

exampasser

tiersten wrote: »

Its normal. The clock generator on your motherboard and CPU will vary slightly due to temperature and manufacturing differences. As the clock multiplier in CPUs now is high along with a high speed clock, you're noticing the variances more than before.

Thanks for the answer, good to know everything is ok.

tiersten

exampasser wrote: »

it's avg max core temp is 62.5c but since AMD max temps for Phenoms are rated by the CPU sensor that's several degrees lower than core I'm safe although a bit hot.

You sure about this? Generally CPUs are rated for a maximum junction temperature. If a core is hotter than that then its not good.

exampasser

tiersten wrote: »

You sure about this? Generally CPUs are rated for a maximum junction temperature. If a core is hotter than that then its not good.

I e-mailed AMD about what they mean by their max temp and they said that their max temp listings are not core temps (at least for the Phenom II's) but overall CPU temp, and my CPU temp sensor (not core) is always a few degrees lower than core.

I also notice that the fan speed throttling is based on my CPU temp sensor on my computer.

tiersten

exampasser wrote: »

I e-mailed AMD about what they mean by their max temp and they said that their max temp listings are not core temps (at least for the Phenom II's) but overall CPU temp, and my CPU temp sensor (not core) is always a few degrees lower than core.

I tried looking for the thermal specifications for the Phenom II X4 955 on the AMD site but I can't find them. The only datasheet I can find is for the original Phenom CPUs. AMD has a useless site for finding information. If I needed to find this information for an Intel CPU it'd be easy.

There are case temperatures and junction temperatures listed for minimum and maximum though.

exampasser

I read on an AMD page that I found on a search, that the max (which apparently means CPU temp) is 62 C.

I'm having trouble finding it again.

Here it is:
http://products.amd.com/en-us/DesktopCPUDetail.aspx?id=618&f1=&f2=&f3=&f4=&f5=&f6=&f7=&f8=&f9=&f10=&f11=&f12=

I also decided to buy a new case fan, hopefully it will push more air than the stock fan at the same automatic speed control voltages:
http://www.amazon.com/Thermaltake-Double-Ball-Bearing-Case/dp/B0006HIMFM/ref=sr_1_1?ie=UTF8&s=electronics&qid=1281047154&sr=8-1

exampasser

Here is the reply from AMD that I dug up from my inbox:

"That is correct. So long as the overall CPU temperature is not above 62* Celsius, then you are within the normal functioning range. However, if you are afraid you are overheating, I still recommend opening your side panel as an experiment to see if the increased airflow improves this.
In order to update this service request, please respond, leaving the service request reference intact.
Best regards,
~Josh
AMD Global Customer Care"

Below is the question that I asked to clarify:

"Just to clarify, if I get a reading above 62 C across all of my core temperature sensors but my CPU temperature sensor remains below 62 C it's operating within it's recommended thermal limits?"