15-Inch MacBook Pro Unites Power with Economy

When it comes to turbo boost, the concept is pretty simple. In this 15-in. model, the processor starts out at 2.4 GHz and stays there unless taxed. If you get into some heavy data-crunching, both cores can throttle up to 2.8 GHz. Or if the software you're using is running on one core instead of two, that lone core can throttle up to 2.93 GHz.

It's like having a turbocharger on your car. If you're cruising along at 65 miles an hour and stomp on the gas, you'll feel an extra spurt of acceleration as the turbocharger kicks in. When you let off the gas, the turbocharger cuts out and you're back to basic cylinders.

Essentially, the system is squeezing out as much processing power as possible from the Core chips when that power is needed most -- under heavy load -- and then backing off the juice when it's not. The result is an elegant combination of power and thriftiness.

Comparisons and Benchmarks

Here's how the Core i5 MacBook Pro stacks up against a Core i5-based iMac and my own 17-in. MacBook Pro, which has a 3.06-GHz Core 2 Duo processor and a superfast SSD drive. The iMac -- unlike the model I reviewed last fall -- has the 2.66-GHz quad-core Core i5 processor. And, unlike this particular MacBook Pro, it has four physical cores and a faster 7,200-rpm hard drive. (The 15-in. MacBook Pro comes with a 5,400-rpm drive.)

First, I did a quick benchmark test of all three computers using Spiny Software's Xbench 1.3. The new MacBook Pro returned a score of 152.03 -- solid, but not stellar. (I expect the relatively slow hard drive is keeping those numbers down.) The iMac, not surprisingly, had a 204.18 score, and my own MacBook Pro topped out at 209 -- largely because of the OCZ Technologies SSD I installed right after I bought it last June. SSDs can throw off benchmarks by artificially inflating scores -- although they do make your computer feel darn fast. More about SSDs below.

Next, I used Primate Labs' Geekbench 2.1.5 to benchmark the three computers. The iMac led the way with a Geekbench score of 6,473. The new MacBook Pro turned in a speedy 4,783. And my own MacBook Pro trailed at 4,192. (Bare Feats did its own tests, in case you want even more data, comparing the faster Core-based MacBook Pros with a Core i7 iMac. The iMac won, by a long shot.)

Although benchmarks can give you a rough idea of how one computer stacks up against others, real-world tasks are usually better for putting a computer through its paces. With that in mind, I opened an 88MB video file in QuickTime and chose the "Save for Web" command. This essentially exports the same video into several different versions at the same time -- and it pegs the processor while doing so. (I use iSlayer's iStat Menus, a great free utility, to monitor what's going on with my computer; it places a series of icons in the menu bar showing you what the CPU is up to, how hot the computer is running, how your network connection is doing, etc.)

Using my own older MacBook Pro -- remember, it has the dual-core Core 2 Duo chip, but a fast SSD drive -- the video export task took 61 seconds. Doing the same thing on my iMac took just 29 seconds. And exporting the video on the new Core i5-based MacBook Pro took 51 seconds.

That might not sound like much of a leap over my last-generation MacBook Pro. But my laptop would have been left even further in the dust if it had a 5,400-rpm hard drive in it instead of an SSD.

If you want more power than the two Core i5 chips offer, you can opt for the 2.66 GHz Core i7. The i7 can spool both cores to 3.06 GHz or, if you're maxing out just one, hit 3.33 GHz. Of course, to get that speed, you'll have to buy the $2,199 15-in. MacBook Pro or get an i7 as an option on the top-end 17-in. model. (The i7 processor would be good for something like high-definition video encoding, because it's 50% faster than the previous generation's 2.8-GHz Core 2 Duo processor, according to Apple.)

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