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I just build myself a new system with a Intel I7 860 CPU. When loading it using a single threaded application like Super PI, CPU-Z shows 2.933Ghz as speed. Now I understood that the I7 goes into turbo boost mode up to 3.46GHz for a single core.
How can I check that? Is there a utility to monitor CPU speed per core?
Jan Derk
Posted 2009-11-28T09:00:08.237
Reputation: 183
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Assuming turbo mode is activated in the BIOS and that you are using a Windows OS, Argus Monitor should tell you when turbo mode is being used.
sblair
Posted 2009-11-28T09:00:08.237
Reputation: 12 231
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CPU-Z should show the extra speed when the turbo mode is activated.
Sathyajith Bhat
Posted 2009-11-28T09:00:08.237
Reputation: 58 436
all cores should have the same frequency – Nathan Fellman – 2010-02-21T11:17:02.330
1@Nathan; No, that's what turbo boost does, overclocks specific, in-use cores. – Phoshi – 2010-02-21T11:27:54.957
No it doesn't. Look here: http://www.intel.com/support/processors/sb/cs-029908.htm where it says: Is turbo frequency the same for all active cores in the processor? Yes
– Nathan Fellman – 2010-02-21T13:34:49.1901@Nathan - What the literature & Phoshi says is that Turbo boost can and will shut down cores which are not in use and apply a spefic frequency boost, across all the cores - ie, if turbo boost is applied on a Quad core with 2 cores being in active, the 2 active cores will get an increase in the same frequency – Sathyajith Bhat – 2010-02-21T15:26:26.663
@Nathan: The keyword is active cores, not just cores – Sathyajith Bhat – 2010-02-21T15:26:50.313
The inactive cores don't have a clock. Talking about frequency with regard to them is meaningless. Even so, when their clocks turn on on the way to becoming active, they will have the same frequency as the others, even if they aren't technically active yet. – Nathan Fellman – 2010-02-21T15:39:02.037
Intel's illustration says otherwise http://www.youtube.com/watch?v=llOXMPXH2VA
– Sathyajith Bhat – 2010-02-21T15:55:08.230The point is, all cores have the same frequency. Some are shut off, but the clock that feeds them has the same frequency for all cores. There's just one central clock, after all, not one per core. – Nathan Fellman – 2010-02-21T19:52:29.980
1@Nathan There's only one BCLK, but a core operates at the BCLK times a multiplier, and each core has its own multiplier. It's the multiplier that's manipulated by Turbo Boost and SpeedStep. On my i7-930, the BCLK is 133 MHz, with a "standard" multiplier of 21 for 2.8 GHz. Tools like TMonitor will show three lightly-loaded cores running at a multiplier of 12 (power conserving) at the same time that another core is running at 22-23x (Turbo Boost, 2.92-3.06 GHz). – coneslayer – 2010-07-30T11:53:23.483
You are right. I was fooled a bit as CPU-Z seemed to show a steady 2940MHz. Testing again with SuperPI it also showed sometimes 3.3 GHz values. And my CPU is rated as 2.8GHz so 2.94 is already a turbo mode. CPU-Z shows an average value for all cores (which varies less) where Argus shows the speed for all cores. – Jan Derk – 2009-11-29T21:06:04.217
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key word here being "active"... so if two cores are INACTIVE, they're at 0mhz
"If I'm watching an orange by complete darkness, its visible color is black." – Gnoupi – 2010-04-22T07:26:59.047
@Gnoupi: actually Matt ain't far off: I'm pretty sure I read an Intel paper where they stated that these newer Core i7 have the ability to entirely shut down unused cores, making them effectively draw zero power (I mean, the article was precisely boasting the fact that unused cores wheren't drawing any power at all). I think in that case it isn't far fetched to say they're at "zero Mhz". Btw your snarky quote is a bit snarky coming from a mod ;) – Weezy – 2010-11-02T15:52:21.727
@weezy - to be fair, I wasn't a mod then, just a regular user. – Gnoupi – 2010-11-02T16:57:02.077
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All cores have the same frequency. See here:
Is turbo frequency the same for all active cores in the processor?
Yes
Nathan Fellman
Posted 2009-11-28T09:00:08.237
Reputation: 8 152
See my comment above. Each core has its own multiplier, which can and does differ from core to core at any moment in time. I believe the meaning of the statement you quote is that no core is special: On an i7-930, all cores have the same turbo frequency of 3.06 GHz. That doesn't mean that they all run at the same frequency all the time. See screenshots at http://www.cpuid.com/softwares/tmonitor.html
– coneslayer – 2010-07-30T11:59:29.537
That is an excellent utility showing the CPU speed and multipliers for all cores. The turbo mode is working fine. – Jan Derk – 2009-11-29T21:01:34.433