i7 sandy bridge CPU when turbo kicks in?

This is my first sandy bridge computer (2720qm) and is curious when do turbo mode actually kicks in?

I run a few benchmarks where CPU got to 100% but never see clock past 2.2ghz (99.77x22), not for a split sec. The temp idle around 40c and 80c at load so I know it is not thermal limitation.

Thanks

 

2.2GHz is the quad core turbo. It'll only get to 2.8GHz when your processor is crunching on a single threaded application.

 

You'll have to run single threaded applications to see your processor hit 3.3ghz, with the other cores near idle. It may only run at that speed for a while until thermal limits cause it to throttle back down. Two cores can hit around 2.8, but all four are limited to 2.2 or so. Practically, you won't see much unless you're running high power single threaded apps.

 

My i7-2720QM clocked around 2,5 GHz when i stressed 8 cores.
It would probably turbo to 2,6 GHz if i enabled max fan speed.

 

Interesting, did you use software like setFSB to OC it to 2.5Ghz or the CPU up clock automatically? Are you sure it is running 8 cores? thanks

 

what a bummer

I seriously thought sandy bridge's turbo works on 4 cores / 8 threads

Now, I am wondering if there is any performance gain compare to my previous qx9300 quad core @ 2.93Ghz 12MB cache

 

Yeah definitely better than that because of improved architecture which outdoes raw clock frequencies.

 

It can technically go higher, to 2.5 or so, but due to the thermal characteristics, it won't stay there for more than a few seconds anyway. Turbo in laptops isn't fantastic because it relies completely on keeping the thermals within a certain threshold before going back to stock. Not seeing much of a boost is due to cooling issues more than anything. But quad running around stock, or maybe 2.3 continuously is about all that's expected when under full load.

 

I'm not sure why this surprised you. This has been the case since the very first desktop i7s came out and turbo mode came out for Intel CPUs.

There's a reason why it's only advertised as a 2.20 GHz CPU. That's because for 4 ores / 8 threads, that's the speed of the chip. If Turbo mode really was straight overclocking, why wouldn't they advertise at 3.0GHz?

As far as if it's better then your QX9300? It depends on what applications you are running. It's a totally newer architecture and faster in more ways that just clock speed. Clock speed is not directly comparable with other generations and classes of CPUs. I can tell you my 2.2GHz i7 2720QM in my laptop gets twice the PCMark score of my desktop Q6600 @ 3.6GHz.

 

If you want to see your turbo kick in easily, check out the emulator from the android SDK, single thread application that maxes a core whenever you do any action.

I've been running other single thread high load applications (mostly emulators) at constant clockspeed of 3.2Ghz for several hours on the P150HM, so I think the turbo thermal constraints aren't even reached, unlike the 2011 macbook pro ^^

 

I am wondering about that too - I am running a calculation on 4 cores overnight, and turbo boost is still reporting a constant 3 Ghz (this is under linux as reported with the i7z utility - which is not an intel tool, so hopefully it is reporting correct values) - the fan is blowing constantly but not at full speed - so it seems there is some slack...

 

It turns out my original interpretation of "turbo" is correct. This CPU does run at 2.5ghz at all time when all 8 threads were stressed full load. So the turbo is not limit to single thread application but to thermal capacity. I was surprised when some suggested the turbo only works on single thread application...

DEangleson, castdead and emphyrio are correct under 8 threads stress, the processor would stay at 3.0ghz for around 30~45 sec and then set at 2.5ghz

 

You can check this thread out.

Heres my results.

Do note that gaming wont stress the CPU enought to clock up to 2,5 GHz on all 8 cores.
Playing BF:BC2 at the settings below my notebook spews out around 90fps on multiplayer maps.
I usually have Vsync enabled, but had to turn it off to actually see how high i could go.