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Apple's latest iMac looks great, even faster

July 1, 2011 06:02 AM ET

The best way to describe the benefits of Thunderbolt is to compare its theoretical speed with current standards: USB 2.0 tops out at 480Mbps, FireWire 800 tops out at 800Mbps, USB 3.0 hits 5Gbps and Thunderbolt maxxes out at a theoretical 10,240Mbps, or 10Gbps. For every connection, there are two bidirectional channels that carry data over a 10Gbps pipe -- each way -- which means you can transfer a lot of data fast.

You can connect a wide variety of peripherals to a Thunderbolt port, from hard drives to displays, daisy-chaining up to six peripherals per port. In fact, it's possible to take a 27-in. iMac and flank it with two 30-in. displays, streaming multiple 1080p hi-def videos from connected RAID enclosures, without hiccups in the data stream. There are a number of real-world examples of how this works.

In addition to serving as a high-speed peripheral port, Thunderbolt can be used for Target Disk Mode and the new Target Display Mode. Target Disk Mode -- you have to hold down the T key while booting up -- has been around for years. It allows you to connect your computer to another one, with the Target Disk Mode machine serving as a hard drive. It allows for quick and easy data retrieval between machines, and being able to do so using Thunderbolt should speed things up considerably.

One more benefit: ThunderBolt is bidirectional, and with these new iMac models Apple has introduced Target Display Mode. In this mode, an iMac can serve as a stand-alone monitor, even if it's still processing tasks. Say you're exporting a large iMovie project using the iMac, but you want to use the iMac's screen as a second display connected to a MacBook Pro. With Target Display Mode, you can do that. This only works with hardware released this year.

Or, rather, it will work. Soonish. Unfortunately, very few Thunderbolt cables and hard drives are shipping, though they're expected to be on the market sometime this summer. (Apple finally released a $49 Thunderbolt cable on Tuesday, as well as an FAQ detailing how it works.) If ThunderBolt delivers on speeds as promised, IT pros who choose to use it will spend far less time waiting for transfers.

Daily use

Theoretical Thunderbolt performance aside, this iMac performs very well under everyday, and even extenuating, circumstances. In a month's worth of use, the iMac I tested never crashed.

iMovie breezed through projects that choke my own Core i7 MacBook Pro (with 8GB ram and a 1TB hard drive). Specifically, I have a complex iMovie project with hundreds of edits. On the MacBook Pro, iMovie's real-time rendering results in garbled audio and long pauses between changes. (In iMovie's defense, however, this is a project that took four hours to render on the iMac, yielding more than an hour of high-definition video in a 5GB h.264 file.) The iMac handled the project without breaking a sweat, a great showing of the raw horsepower of the new Sandy Bridge processor.

I've been reviewing Macs for some time now, and for consistency's sake, I have a complex, 50-minute iMovie project that I like to render on every Mac I review. (The iMovie file was exported using Apple's "Large" settings, resulting in an h.264 m4v file with a resolution of 960 by 540 pixels.) Last year's high-end iMac -- a 2.8GHz quadcore i5 -- rendered the movie project in an hour and eight minutes. The iMac I tested did it in just 48 minutes.

What a difference a few months makes. Of course, that kind of speed boost is less apparent when doing more mundane work like checking email, surfing the Web or watching videos full-screen. And while the HD webcam is nice for video chats, it won't do any good unless the person you're chatting with also has a recent Apple computer with the same camera. Sure, you'll look great to the other person. But you'll see them in regular definition video.

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