topic Core Speed Issue? in Software Tuning, Performance Optimization & Platform Monitoring

Core Speed Issue?

thebanker101 — Mon, 19 Mar 2012 03:03:41 GMT

Hello Intel community,

I have a quick question regarding my Intel Core i7 2700k. I have a program, which many have probably now heard about, named CPU-Z. I have used this to monitor my cpu core speed and the core speed has been showing up at 1596 MHz, the core i7 should be around 3500MHz. May I remind you this is when nothing is running, however, the speed keeps changing back and forth from 1596MHz to 3792MHz. This is a strange flunctuation and since I still havn't had it for over 30 days, I am planning to RMA back. Is this an issue? And should I RMA it or is there an option somewhere to change a certain setting? Thank you very much for reading this.

Thebanker101

Core Speed Issue?

Patrick_F_Intel1 — Mon, 19 Mar 2012 12:11:29 GMT

Hello thebanker101,
This sounds like expected behavior.
The CPU reduces the frequency when it is idle in order to save power.
When the processor has sufficient work to do then it bumps up the frequency.

The reference frequency is 3.5 GHz.
In Turbo mode the frequency further increases up to 3.8 GHz.

If you want to check that the CPU is behaving properly, you can busy up the CPUs and you should see the CPU frequency jump up.
The test program you choose should be something that keeps the CPU busy long enough (like a few seconds or more) so you have time to see the change with CPU-Z.
Most programs do IO (reads and writes to disk) and IO usually has lots of idle time.

You can use the 'stream' memory benchmark to busy up your system.
A windows binary is available at http://www.cs.virginia.edu/stream/FTP/Contrib/Intel/win32/wstream.exe
Download it and run it with the command line 'wstream.exe 3500 1000' (where 3500 is your cpu freq in MHz and 1000 is the number of iterations to run)
This will keep the cpu VERY busy for a while. CPU-Z might not even update its display until the wstream is done.
Hope this helps,
Pat

Core Speed Issue?

revogirl — Mon, 23 Apr 2012 12:28:21 GMT

The 'Maximum Turbo Frequency' of an Intel Core i7-2700K is 3.9 GHz Not 3.8 GHz. That aside. It all depends on your (UEFI)BIOS settings, but it is normal to idle at ~1600MHz (16 * 100 MHz). Small variation are normal. You mentioned that it steps (that's Intel Speedstep technology) from the lowest possible (idle) P-State to the maximum non-turbo clock speed of 3.5 GHz. Again. This sounds about right. Turbo isn't kicking in, apparently, so you better check your (UEFI)BIOS settings. Make sure Intel Speedstep and Turbo ratios are both enbled, and try experimenting with the turbo ratios you can use one or four different values there.

BTW: You didn't mention what OS you are using (me working with Apple) so I assumed Windows hence your usage of CPU-Z.

Anyway. I hope this helps ;)

Link to datasheet:http://ark.intel.com/products/61275