CPU-Z says one thing. Core Temp Says another?

Question

Im struggling to understand my i5 750's real time speed. Its classified as a 2.66, Windows system properties says 2.67mhz.

CPU-Z is telling me that my "core speed" is changing randomly non stop from 1555mhz all the way through to 3199mhz.

I understand the idling business, when its not doing anything it idles out to around 1555mhz. but even when idling, it fluctuates between 1555 & 2999mhz. a bit abnormal for not doing anything.

A bit worrying, For a cpu to idle between those rate. When in game or using the 720p HD 600 cam from microsoft it registers from 2900mhz to 3199mhz, never gets to 3.2.

I also use Core Temp to give me a readout of the temps as im working on desktop. Usually very good, never goes to 50 or above, don't know about in-game :) but its nice out of game.
But Core Temp is telling me at the same time as CPU-Z that my frequency when under load is around 2799mhz, even while CPU-z says 3199mhz. give or take the odd few mhz here n there :)

What is the difference between the CPU-Z Core Speed & Core Temp's Frequency. Are they reporting the same thing. and if so, why do I get such random readings from as low as 1555 to 3199mhz.
I understand that there is a discrepancy between the two programs and the time it takes them to read the speed on the fly, but what I don't understand is.

1. Why does the i5 750 idle at those weird rates.

2. Is frequency from core temp software the same as Core Speed on CPU-Z. Are they reading the actual speed of my CPU?

3. The CPU is rated at 2.66 yet it runs up to 3.1 when in game or under load. I have never Overclocked anything. The only thing I have done was update the BIOS tot eh latest version in hopes that it might fix this.

4. Is it actually running at 3.1 when under load or is it something else, like FSB ? FSB for my board states in the BIOS that its 4100mhz or something like that, but defiantly over 4000MHz.
Also CPU-Z has something called QPI Link, And that seems to look like my CPU's normal running parameters. 1.66 to 2.66mhz Its just confusing with all the googling and all the different answers.

I know this is a bit of a mouthful hehe, but if anyone can read this and see my point it would be great.
Im just struggling to see what my actual speed is. Speed Detection software says up to 2677, some others say 2799mhz.

Only reason I go so in depth is that ive wanted to OC for a while, but simply don't have the income to replace broken parts or invest in water cooling only the basic to intermediate cooling, like the copper pipe idea with giant fan :) Using arctic cooler pro something something lol.

And Ive noticed that the multiplier on CPU-Z reports when under load as high as x24. I know that OC'ing a CPU involve voltages and changing the multiplier.

If my cpu is running normal, then why is the multiplier changing so often, even when idle. from as low as 1555 to 2999mhz.

Any help if at all would be great. sorry for the long winded text, but Im just stuck trying to figure out if my CPU is Overclocking itself on the fly.. even though the temps are very low.

Thanks in advanced. Dan

Answer 1

The only explanation to why the cpu clocks itself to those rates that I can find is that you have some kind of a power saving function that downclocks the cpu in idle, and that, when it gets a little load, Turbo Mode kicks in, slightly overclocking one of the cores.



I would suggest that they are measuring diffrent cores, as turbo mode only affects one core, and the load may vary, the other cores may be affected by the energy saving functions that causes these readings.



FSB, or front side bus, is the frequency that the cpu communicates with the north bridge (motherboard). It should clock itself to the same level as the cpu. If it's rated to 4200 MHz, that's probably as high as your motherboard supports overclocking your cpu, meaning it's not clocked at 4200 MHz currently.



Overclocking tutorial (IF you have a P55 Motherboard): http://www.youtube.com/watch?v=I6zANFlYEDM



Not sure what cooler you have, but there are many good ones out there for 60$... Noctua is a very good brand, but there are others. Check reviews.

These two reviewers are great:

http://www.youtube.com/user/TimeToLiveCustoms

http://www.youtube.com/user/LinusTechTips?feature=chclk

Personally, I would stay away from this guy, as he has a tendency to give everything a 100% KICKASS badge. Very professional reviews though.

http://www.youtube.com/user/3DGAMEMAN?blend=1&ob=5

Answer 2

Cpu Z Temp

Answer 3

Cpuz Temp

Answer 4

The skill that the temperature of the case can't exceed seventy two.6C. there is not any way for us to grant you clever spec suggestions devoid of understanding the specifics of your situation. what's your CPU voltage? what's your case or center temperature at finished load?