By Prince McLean

Published: 10:00 AM EST (07:00 AM PST)

Apple's latest high-end iMac gets a stunning, huge, cinematic 16:9 27" screen, fast Core i5 and i7 CPU options, a standard wireless keyboard and Magic Mouse, a staggering 16GB RAM capacity, a new video input feature, and an environmentally friendly design at all a new lower price.

Position in the Mac family

The latest iMacs advance Apple's consumer flagship offering into high performance territory, offering Intel "Nehalem" Core i5 and Core i7 quad-core processors as options to the standard dual-core Core 2 Duo CPUs also used in the Mac mini and MacBook lines. Previously, Apple only offered quad-core Nehalem family chips in its Xeon-based Mac Pro and Xserve models, both of which were introduced this spring.

While these new chips run at a slower clock speed (Apple offers the 27" iMac with a Core i5 at 2.66GHz or the Core i7 at 2.8 GHz, while its Core 2 Duo offerings are clocked at 3.06 or 3.33GHz), they achieve higher performance from the use of more cores (four, rather than two on the Core 2 Duo), more onboard CPU cache RAM built into the chip (8MB rather than 3 or 6MB on the Core 2 Duo), and the Nehelem's new QuickPath memory architecture, which includes a direct memory controller on the CPU rather than having the processor talk to RAM via its external chipset.

This change, which applies only to the i5 and i7 CPU options, subverts Apple's current strategy of using NVIDIA's 9400M across the board to provide its Macs with both standard chipset functions (such as providing a memory controller, SATA, USB, PCIe, audio, and networking functions) and graphics features. The Core 2 Duo version of the 21.5" and 27" iMac continues to use the 9400M design, which is also used in the Mac mini and all MacBook models.

Apple cites SPEC CPU2006 benchmarks showing that the fast CPU and memory architecture of the new high end 2.8GHz Core i7 option delivers 2.4 times the computing power in both floating-point and integer calculations relative to the 3.06GHz Core 2 Duo.

The higher end of the latest iMacs also offer a big boost in graphics performance over the standard 9400M, which is designed to share 256MB of the system's main memory. Both of the new iMac models offer the ATI Radeon HD 4670 dedicated graphics processor with 256MB of its own graphics RAM, which delivers 2 to 4.4 times the performance of the 9400M architecture. The 27" iMac also provides an option for the ATI Radeon HD 4850, which is yet again rated to deliver 1.5 to 1.8 times the performance of the 4670, thanks in part to packing twice as much dedicated graphics RAM: 512MB.

Comparable Windows PCs often pack on even more graphics RAM. For example, Acer's similarly equipped Gateway One supplies the same ATI Radeon HD 4670 with 1GB of dedicated graphics RAM. This primarily benefits video games, as it allows the game to load texture maps and other data into graphics RAM for optimal performance. Apple's iMacs are designed more to be digital media hubs running iLife and other creative apps, which aren't as hungry for graphics RAM. The company still touts video game play on its iMac systems, but hardcore gamers are not likely to be shopping for Macs given that most games are tied to Windows. Even so, the iMac's option for 512MB of graphics RAM is not a serious limitation even for users who plan to run Windows PC games natively using Boot Camp.

Base models of the iMac ship with 1TB 7200 RPM SATA hard drives and offer an identical 2TB upgrade option (apart from the entry level 21.5" model, which ships with a 500GB hard drive). All models also ship with 4GB of RAM, expandable to 8GB on the 21.5" model and a whopping, officially supported 16GB on the 27" iMac. Prices range from $1199 or $1499 for the 21.5" iMac to $1699 or $1999 for the 27" model.

CPU upgrades cost a $200 premium, the video card bump costs $150, while the 2TB disk is a rather expensive $250 option. Market prices for 2TB drives at retail are currently close to $180 (and you can keep your existing 1TB disk). However, Apple's RAM upgrades are now, in a very atypical departure for the company, set closer to regular market prices, albeit still astoundingly expensive on the high end because high density, fast 4GB parts are still new on the market.

Maxing out the RAM to 16GB costs $1400 from Apple, while the same amount of RAM (4x4GB 1066GHz DDR3, PC3-8500) currently costs about $1480 from third party Mac-oriented RAM dealers on the web and around $1000 from generic sources (OWC contacted us since the review to point out they sell a 16GB RAM upgrade for just under $1000, about 2/3rd of Apple's price).

Since the 27" iMac provides four RAM slots, users have the option to upgrade incrementally without having to throw away RAM to make room for new parts.

The iMac's expansion potential positions it clearly ahead of the compact, entry level Mac mini, which can be upgraded by users but is not really designed to be user serviceable. The Mac Pro delivers still greater upgrade options, with room for 4 hard drives; dual optical drives; two quad-core processors; a double-wide, 16-lane PCI Express 2.0 graphics slot and two 4-lane PCI Express 2.0 slots; up to 32GB of installed RAM; and additional Ethernet and FireWire 800 ports. Of course, the Mac Pro is also significantly more expensive even without a display.

The glossy LED-backlit screen

The biggest new feature of the new iMac is its massive screen, which jumps from the previous high end of 24" to 27" and delivers nearly the resolution (2560x1440) of the 30" Cinema Display HD (2560x1600). That's currently the largest display available from any all-in-one PC vendor, and nearly equivalent to four 13.3" MacBook screens (1280x800) in a single display. The new iMac is still priced $100 less than Apple's standalone 30" big screen display, despite packing in a powerful computer and new LED backlighting.

Compared to Apple's older 20" Cinema Display, the new screen delivers higher screen density and a significantly brighter display. The photo below shows that the same web browser window that consumes the entire 20" external display appears slightly more compact on the built-in screen, where it only takes up about two thirds of the screen.



The new 27" iMac, along with its smaller 21.5" partner, sport higher quality IPS LCD screen technology, resulting in spectacular color, contrast and wide viewing angles. Like previous models, the glossy screen is covered with a glass panel that extends across the entire top face of the unit. The new models also sport less of a chin than previous iMac, giving them a more balanced overall appearance.

Last year, Apple was sued over its iMacs for using cheaper, 6-bit TN ("twisted nematic") screens, which have a narrower viewing angle and less color accuracy and depth, because some users argued the screens were technically incapable of actually producing the "millions of colors" supported by the machines' graphics cards. The latest models reverse the trend toward cheap displays and instead provide quality IPS ("in-plane switching") panels that deliver much-improved color and a wide, 178 degree viewing angle both horizontally and vertically.

The new screens are also LED backlit (unlike the 30" Cinema Display HD), which means they turn on instantly and allow for finer grained control over brightness than conventional cold cathode fluorescent lamp backlighting. LED backlighting is also environmentally friendly because it uses no toxic mercury. Overall, the new machines also meet Energy Star 5.0 and EPEAT Gold standards for energy efficiency and environmentally-sound design, manufacturing, and use of recyclable materials.

The new 27" display is backed by ATI Radeon HD 4670 (or for $150 more, the 4850) graphics hardware equipped with 256MB (or 512MB) of GDDR3 RAM. It supports video output up to 2560x1600, capable of driving a 30" Cinema Display HD. It supports VGA, DVI/HDMI and DisplayPort screens via its standard Mini DisplayPort connector.

A new feature of the 27" iMac is its ability to act as a display for another DisplayPort computer. It is the first and currently the only Mac to support this new capability. The 21.5" iMac doesn't support video input and provides simpler NVIDIA GeForce 9400M graphics on the low end, the same as Apple's MacBook line and Mac mini.

Because the new 27" iMac is now priced less than the aging 30" Cinema Display HD with a similar resolution, it makes sense for users who need a big external screen to buy it instead and gain a free rendering machine capable of running Xgrid or Qmaster distributed processing tasks in the background as a free bonus. When connected to a DisplayPort output device, the iMac's screen can be switched between the internal computer and the external video source. Currently, this only allows the new iMac to serve as a display for late-modeled Macs and other PCs capable of DisplayPort output. In the future, other devices such as new Blu-Ray players will likely become possible to use as DisplayPort output sources for the iMac's display.




On page 2 of 3: Wireless Apple Keyboard and Magic Mouse; and Performance overview: RAM, HD and CPU.