Review: 27-inch iMac mixes advancements, compromises

Apple's largest all-in-one desktop computer, the 27-inch iMac, was recently updated with a long list of under-the-hood changes, but it's the strikingly thin design that people notice first. And while the 5mm edge on the new iMac is certainly impressive, you can't help but wonder if the tradeoffs Apple made for the new design are worth it.

The specifics

Apple has two standard configurations of the new 27-inch iMacs. Both use Intel's quad-core Ivy Bridge processors; the high-end $1999 model sports a 3.2GHz Core i5 processor, while the low-end $1799 model uses a 2.9GHz Core i5. Our tests showed that the 3.2GHz model was between 5 and 7 percent faster in processor-intensive tasks. Both processors support Turbo Boost to run at speeds of 3.6GHz for brief periods of time. For an additional $200, the high-end model can be configured to order (CTO) with a 3.4GHz quad-core Core i7 processor that supports Turbo Boost up to 3.9GHz. The optional Core i7 also supports Intel's Hyper-Threading technology that allows two virtual processing cores to run on each physical core, so applications that can take advantage of multiple cores can address eight virtual cores instead of the four physical.

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All 2012 iMacs ship with 8GB of RAM, up from 4GB in the previous generation. The 27-inch iMacs both ship with 7200-rpm, 1TB hard drives as standard equipment--the same as the 2011 27-inch iMac.

Unlike the new 21.5-inch iMacs, the larger models still have user-configurable memory. An interesting trap door mechanism on the back of the 27-inch iMac, just above the power cord input, gives access to the four memory slots. The 27-inch iMac's 8GB of RAM comes in the form of two 4GB SO-DIMMs, leaving two slots open. If you want to increase the RAM to 16GB, Apple will do it for you for $200 at the time of purchase. But since you have two open RAM slots and installation is so easy, I'd recommend looking at a third party for more economical RAM upgrades. For example, OWC offers two compatible 4GB SO-DIMMS for $60, and Crucial sells two 8GB SO-DIMMS for $86.

The new iMac has four USB ports, the same number as the 2011 model, but the ports have been updated to USB 3. The new iMac still has a gigabit ethernet port and a headphone/audio-out port on the back, but an audio-in port is no longer provided. FireWire is also absent from the new iMac, meaning you'll need to purchase a Thunderbolt to FireWire adapter. Speaking of Thunderbolt, the new iMac has two Thunderbolt ports, which is convenient if you want to connect multiple Thunderbolt devices like displays and hard drives. The handy SDXC card slot has moved from the side of the iMac to a less convenient spot on the back of the iMac, near the ports. If you want to burn, rip, watch, listen, or back up to CDs or DVDs, you'll need to purchase an external optical drive, such as Apple's $79 USB SuperDrive--the new iMacs follow Apple's trend away from internal optical drives.

Apple has also updated the iMac's graphics processors, opting for Nvidia over AMD this year. The $1799 model uses the Nvidia GeForce GTX 660M with 512MB GDDR5 memory, while the $1999 iMac uses an Nvidia GeForce GTX 675MX with 1GB GDDR5 memory. The extra graphics RAM in the higher-end iMac helped it post higher frame rates in games like Portal 2 than the $1799 model, but only marginally so. The high-end iMac can be upgraded for $150 to the Nvidia GeForce GTX 680MX with 2GB GDDR5 memory. The new graphics were faster than the 2011 AMD graphics in games like Portal 2, but were slower in our tests using Cinebench's OpenGL benchmark.

2012 27-inch iMacs: Speedmark scores

No reflection on you

As part of the iMac's physical redesign, Apple eliminated the 2mm air gap that used to exist between the iMac's glass cover and the LCD panel. Now, the glass is directly adhered to the panel, which helps reduce glare and reflection but makes it expensive to replace the front glass--if the glass breaks, the whole display must be replaced. Only the bravest of souls were willing to open an iMac previously, but the new design's use of adhesive instead of magnets to connect the screen to the case basically locks the iMac down to all but certified repair folk.

One positive benefit of this major design change--in cooperation with a new anti-glare coating process--is a very noticeable reduction in screen reflection. Apple claims a believable 75 percent reduction in glare. Standing in front of two iMacs, one a 2011 iMac and the other a 2012 model, it was almost like looking into a mirror on the older system, while my reflection virtually disappeared when moving in front of the 2012 model.

Luckily, colors on the new iMacs still look vibrant and photographic images pop, with dark blacks adding the appearance of depth. The iMac's LED backlit IPS display, with a native resolution of 2560 by 1440 pixels, has a wide viewing angle that lets you and several others collaborate around the iMac screen with very little loss of contrast or color shifts as you move from the center of the screen.

The iMacs integrated speakers also received an upgrade. Music sounded noticeably warmer and fuller on the new system's stereo speakers. Video conferencing was enhanced by increasing the resolution of the built-in FaceTime camera to 720p and adding a second microphone that helps to eliminate background noise and improve audio quality.

Drive issues

As mentioned in our review of the new 21.5-inch iMac, those models switched from using 7200-rpm hard drives to slower 5400-rpm drives. The 27-inch iMacs kept their (relatively) speedier 7200-rpm drives, so performance wasn't adversely affected when comparing the new models to their predecessors.

We did, however, find an unexpected difference between the hard drives used in the two iMacs. Although not a specification quoted by Apple, one of the hard drives had twice the amount of on-board cache as the other and performed significantly better. Unfortunately, this faster hard drive (a Seagate Barracuda ST1000DM003 with 64MB of cache) was found inside the low-end $1799 iMac. A slower drive (a Western Digital WD10EALX Caviar Blue with 32MB of cache) shipped in our high-end iMac.

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