i5 and i7 turbo boost....

OK...
I sold my 13" macbook because it was a bit too small for for my eyes liking. With what I thought was decent research, I selected the 15" with the 2.4GHz i5. The machine works quite well, however I am getting a bit of buyer's remorse after learning the advantages of the i7 with regard to turbo boosting.

Help me understand....

Does the i5 2.4GHz automatically go to single core when boosting, or are there steps, as with the i7 (2.66-3.06 dual core, 3.33 single)?

TIA,
david

Turbo boost works like it does on the i7. The mobile i5-520M can run 2.933GHz max with 1 core loaded and something above 2.4GHz depending on the power consumed by the task.

The mobile i7-720QM runs at 1.6GHz and can turbo boost up to 2.8GHz. There's an extreme mobile i7-920XM that runs at 2GHz with a max turbo frequency of 3,2GHz, but it has a 55W TDP and I don't think Apple uses it.

Quad core certainly can come in handy, but it depends on what you run and whether it's worth the extra $400 (ouch) to you. The reason I wrote ouch is because the i5-520M costs $225 and the i7-720QM costs $364. Not $364 more, just $364.

Are there any intermittent steps with the i5 520 where it is a boosted as a dual core? Indeed, Apple and others charge a premium for their chip upgrades.

The mobile quad core is, of course, not presently available on Mac. It too, loses cores as it boosts (2.8 is single).

Yeah, as long as it stays within the power limits, which is how turbo boost works. There are 4 steps above 2.4GHz: 2.53GHz, 2.66GHz, 2.8GHz and 2.93GHz. A heavy 4 thread task may cause the processor to run at 2.4GHz, while a 2 thread task spread across 2 cores may run at 2.8GHz or lower, down to the minimum speedstep multiplier, depending on the CPU load.

http://store.apple.com/us/configure/MC373LL/A?mco=MTc0Njg1ODE <-- I see what you mean now. I forgot about the i7-620M dual core since almost nobody sells laptops with those. The price difference bewteen the 620M and 720QM is about $30. Power consumption is probably the issue, even though there is only a 10W difference.

Finally found my answer.....

"The whole process works like this. If you have all cores active and the workload they&#8217;re running isn&#8217;t maxing out the CPU&#8217;s specified current or power draw, the cores can run at a higher frequency. If you have only one core active, the other core is power gated (effectively shut off) and the active core is allowed to turbo up several bins as long as it remains within its current, temperature and power limits.

The result is that most of the time your 2.40GHz Core i5 runs at 2.66GHz, and if you&#8217;re only running single threaded applications you&#8217;ll see it bounce from 2.66GHz to 2.80GHz and 2.93GHz. So even if the IPC improvements brought on by Arrandale weren&#8217;t enough, you&#8217;ll rarely run at your base clock speed when you need the performance. Intel&#8217;s Turbo Boost works beautifully in practice and the transition to OS X seems to have gone well."