24-inch iMac Core 2 Duo/2.16GHz

The iMac was originally conceived as a relatively compact all-in-one computer, and that was a large part of its appeal. Compact, however, is not word most people would use to describe the 24-inch iMac, which features the latest Apple technology packed behind a massive flat-panel display. But for people who want a fairly professional system without making the jump to a Mac Pro, the new large-screen iMac fills a tempting middle ground. It gives you impressive performance, but without the expansion options of a pro tower.

The (really) big picture

Sitting on a desk, the 24-inch iMac is monumental. Its large, widescreen display offers a resolution of 1920-by-1200 pixels, the same as Apple’s $999 23-inch Cinema HD Display (   ). And as with Apple’s 23-inch display, the iMac has enough resolution to show off many windows, palettes, and every pixel of full 1080 high-definition video (with some vertical pixels left over for good measure). Compared to the previous largest iMac, the 20-inch model, this one has 30 percent more pixels.

But as with most of Apple’s new displays, the 24-inch iMac isn’t just about gaining more screen real estate. Its display is roughly 43 percent brighter than the new 20-inch model, with the same 400 candelas per square meter (also called nits ) as Apple’s 23-inch and 30-inch (   ) displays. The brightness of this screen is very pleasing.

Even with the gigantic display, however, the iMac feels sturdy and well balanced. With its thin design, the iMac weighs only 24.7 pounds, just 2.7 pounds more than the 20-inch model.

What’s inside

The 24-inch iMac has a 64-bit, 2.16GHz Intel Core 2 Duo processor with 4MB of shared L2 cache (twice the cache of the Core Duo iMacs), connected to the system with a 667MHz frontside bus. It comes standard with 1GB of 667MHz DDR2 SDRAM, although that RAM is split between two 512MB DIMMs. This means any subsequent upgrades will require tossing at least one of the DIMMs to make room, making upgrades more expensive. Also, the Intel chipset that Apple uses in the iMac means the operating system can address only 3GB of RAM, even if you were to put two 2GB DIMMs inside.

The iMac also comes with a 250GB Serial ATA hard drive, an 8x double-layer SuperDrive, and Nvidia GeForce 7300 GT graphics with 128MB of GDDR3 memory. It includes built-in AirPort Extreme and Bluetooth 2.0 wireless networking, mini-DVI video output, an iSight camera, an Apple Remote, three USB 2.0 ports, (plus two USB 1.1 ports on the keyboard) one FireWire 400 port, one FireWire 800 port (good for swift connection to storage devices), Gigabit Ethernet, and combo ports for analog and digital audio input and output (previous iMacs had analog-only audio input).

Performance

To see how well the top-of-the-line iMac performs, the Macworld Lab put it through our standard suite of tests. The 24-inch iMac garnered an impressive Speedmark score of 245, only nine points below the 2GHz Mac Pro (not surprisingly, the 24-inch iMac earned the same Speedmark score as the new 20-inch model, which has the same processor).

Judging from the test scores, the 24-inch iMac seems to bridge the performance gap between standard iMacs and Mac Pros. Compared to the previous high-end iMac—the 20-inch 2.0GHz Core Duo model—the 24-inch iMac showed a nearly 17 percent overall Speedmark improvement. Most impressively, our MPEG-2 encoding test using Apple’s Compressor was 28 percent faster than the old 20-inch model, and the Cinema 4D Render test showed a 14 percent jump—good numbers for pro-level use.

Another big improvement is that the new iMac pumped out more than 25 additional frames per second in our Unreal Tournament test, a nearly 47 percent boost in frame rate over the 20-inch Core Duo model. The included Nvidia graphics chip is good news for anyone who likes to play games. (Users interested in the best performance can replace the 7300 GT with the GeForce 7600 GT with 256MB of video memory for an additional $125, making this the first iMac with an option to upgrade to a different graphics processor.)

As with all current Macs, software that hasn’t been updated to run natively on Intel processors runs more slowly than it would on a PowerPC chip. But the new iMac completed our suite of 14 tasks using Adobe Photoshop CS2 in 24 percent less time than the old 20-inch model—a respectable jump.

Quick operations

For general operations, the 24-inch iMac’s overall responsiveness was excellent. Opening, dragging, and resizing windows was very quick. HD video playback was smooth, and working in Intel-native applications such as Final Cut Pro (   ), Motion (   ), iMovie (   ), and iWeb (   ) was snappy. (You can custom configure a 24-inch model with a 2.33GHz Core 2 Duo processor for an extra $250. Our benchmark chart shows the performance improvements you’ll see with this faster chip.)

The 24-inch iMac also has an upgraded sound system, with a 24-watt digital amplifier (twice that of the other models) to power the built-in stereo speakers. The sound was much louder than on any other iMac I’ve used—useful for, say, watching a movie from across the room—and it had fairly good quality. (Audiophiles will still probably want a separate set of powered computer speakers or want to connect the iMac’s digital audio output to a good home-theater system.)

Macworld’s buying advice

The 24-inch iMac occupies the vast stretch between the smaller iMacs and the Mac Pro (   ). Since it scores basically the same as the 20-inch iMac, the $500 difference gives you a larger and brighter display, a FireWire 800 port, and a better graphics system. Compared to the Mac Pro, you gain a built-in display and a degree of portability, but you sacrifice the Mac Pro’s quad processing and significant internal expansion options. If you’re looking for the ultimate iMac with a taste of the pro-level features the Mac Pro provides, you’ll find the 24-inch iMac to be the perfect middle ground.

[ Jonathan Seff is Macworld ’s senior news editor. ]