Wed, 19 Dec 2012 Apple iMac (Late 2012) review (21.5- and 27-inch)

New iMac performance

While the new thin-edged iMacs are things of beauty that alone is not going to impress most of us enough to upgrade our current iMacs.

So how fast are the new iMacs?

[Benchmark testing by Macworld.com’s James Galbraith, Albert Filice, and Kean Bartelman. Performace write up by James Galbraith.]

The new iMac models come with Intel’s Ivy Bridge quad-core processors that share 6MB of L3 cache.

21.5-inch iMac speed tests

The £1,099 21.5-inch iMac has a 2.7GHz Core i5 processor, while the £1,249 21.5-inch iMac has a 2.9GHz Core i5 processor. The processors support Intel’s Turbo Boost, which allows a processor to run faster (up to 3.6GHz on the £1,249 iMac and 3.2GHz in the £1,099 iMac) with processor-hungry applications.

The optional 3.1GHz Core i7 quad-core processor, a £160 upgrade to the £1,249 model, offers Intel’s Hyper Threading. This allows applications to address twice as many virtual processing cores, helpful in applications that can take advantage of multiple cores like Mathematica and Cinema4D.

In the Macworld Lab the new high-end 21.5-inch 2.9GHz iMac was 12 percent faster than the previous high-end 21.5-inch iMac with a Sandy Bridge 2.7GHz Core i5 quad-core processor in our MathematicaMark tests and 17 percent faster in the Cinebench CPU test.

The new entry-level 21.5-inch 2.7GHz iMac was 11 percent faster than the previous entry level 21.5-inch iMac with a Sandy Bridge 2.5GHz in both MathematicaMark and Cinebench CPU tests.

Apple also updated the graphics processors in the new iMacs. The ATI Radeon has been replaced by Nvidia graphics processors: the GeForce GT640M in the £1,099 model (21.5-inch), and the GeForce GT650M in the £1,249 model (21.5-inch).

The 27-inch £1,499 iMac comes with the same GeForce GT650M as the upper-end 21.5-inch model. The £1,699 27-inch iMac comes with a 1GB GeForce GTX 675MX, which for an extra £120 can be configured to a GTX680MX with 2GB GDDR5.

Our Portal 2 test results were 7 to 8 frames per second faster on the new iMacs when compared to the previous models, but the Cinebench OpenGL test results were 10 and 12 percent slower than the previous low and high-end iMacs, respectively.

27-inch iMac speed tests

Both 27in iMacs include 7,200rpm, 1TB SATA-3 hard drives, but the drives in these two iMacs we received are not identical — and neither were their performance scores.

Our £1,699 iMac has a Western Digital WD10EALX Caviar Blue drive with 32MB of cache. Our £1,499 iMac has a Seagate Barracuda ST1000DM003 hard drive with 64MB of cache—twice the cache of the WD, and the advantage of the larger cache is evident in our test results.

The £1,499 iMac was 34 percent faster than the £1,699 iMac in the 2GB folder copy test, and 20 percent faster when uncompressing a 6GB file. In fact, the £1,499 iMac was faster than the £1,699 iMac in nine of the 15 tests that make up our Speedmark 8 benchmark suite. The £1,499 iMac had an overall Speedmark 8 score that is 6 percent higher than the £1,699 iMac.

As a reality check, we ran Blackmagic’s Disk Speed Test, using the 5GB file settings. We found read and write speeds between 180MBps to 190MBps on the Seagate hard drive, and about 120MBps on the WD drive.

When put into context with the results of the 2011 iMacs, this doesn’t seem to be a case of Apple choosing slower drives for the high-end model, it’s just that the Seagate drive is very fast. The £1,499 iMac took 96 seconds to copy a 6GB file from one part of the drive to another, while the WD drive in the £1,699 iMac took 146 seconds, the same result as the high-end 2011 27-inch iMac.

While the Seagate drive is fast, it’s nowhere near as fast as the Fusion Drive in our custom-built 2012 27-inch iMac, which finished the 6GB file copy in just 41 seconds and had Blackmagic write speeds of over 310MBps and read speeds of over 400MBps.

In better news for the £1,699 iMac, it was faster than the £1,499 iMac in both the Cinebench CPU test (7 percent faster) and MathematicaMark (5 percent faster). The £1,699 iMac was also faster than its predecessor, a 3.1GHz Sandy Bridge quad-core Core i5 system.

This year’s model was 19 percent faster overall than the 2011 high-end iMac, 14 percent faster in the Cinebench CPU test, and 16 percent faster in our Handbrake test—the extra RAM in the 2012 standard configuration helps boost performance. (The 2011 iMacs came with 4GB of RAM.) TheVMWare/ PCMark test loves that extra memory. The new £1,499 iMac 2012 was 28 percent faster overall than its predecessor, a 2.7GHz Sandy Bridge quad-core Core i5 system. The new £1,499 iMac’s zippy hard drive, larger amount RAM, and faster CPU all contribute to its increased speed.

The 2011 iMac used AMD Radeon graphics, but Apple, as they are wont to do, has switched alliances for this generation, going with an Nvidia GeForce GTX 660M with 512MB GDDR5 memory in the £1,499 model, and an Nvidia GeForce GTX 675MX with 1GB GDDR5 memory in the £1,699 model. (The £1,699 iMac can be upgraded to 2GB of video memory for an additional £120.)

The graphics test results were mixed; Cinebench’s OpenGL test showed the older Radeon graphics to be about 6 percent faster than the new Nvidia graphics on the £1,699 iMac, and 11 percent faster on the £1,499 iMac. Portal 2 test results showed the opposite effect, with the new Nvidia graphics showing a 7 percent advantage over the older Radeon graphics in the high-end models and 6 percent in the low-end models.

Our customized 2012 iMac with a 3.4GHz Core i7 processor, 1TB Fusion Drive, and 16GB of RAM, was 40 percent faster overall than the standard £1,699 iMac, and 32 percent faster than the £1,499 iMac. The Core i7’s Hyper Threading helped the custom iMac post Cinebench CPU scores that were 24 percent faster than the £1,699 iMac and 29 percent faster scores than the £1,499 27-inch iMac.

New iMac: hard drive speeds

Because of the reduced case size, Apple uses smaller 2.5-inch 5,400-rpm hard drives in the new 21.5-inch iMacs, where Apple previously used 3.5-inch 7,200-rpm drives.

The 27-inch iMacs still use 3.5-inch 7,200-rpm hard drives.

Apple increased the cache size on these slower-spinning drives to help increase the performance. But even with the larger cache, the older iMac’s 7,200-rpm drives finished our file copy test faster than the new iMac’s 5,400-rpm drives. The file unzip test was just 1 percent faster on the 2011 iMac.

If you want faster drive speed, as well as zippier startup and application launches, the new £1,249 21.5-inch iMac can be outfitted with Apple’s 1TB Fusion Drive for an extra £200.

Fusion Drive combines fast flash storage with high capacity hard drives and presents the two as one drive to the user and software. The OS and all applications that come with an iMac are loaded onto the flash portion of the Fusion Drive, making application launches and restarts much faster than with a standard hard drive.

In our testing we found that most tasks on a Fusion Drive perform at the same speeds as a standalone solid-state drive, even with 600GB of data loaded onto the drive.

Long extended writes and reads will eventually hit the bottleneck created by slower hard drive speeds, as you’d expect. Previous testing showed Fusion Drives able to finish our 6GB file copy tests in about 40 seconds, while the 5,400-rpm hard drive in the iMac took around 150 seconds to complete.

Fusion Drive is not available on the 21.5-inch £1,099 model, but is on all other models in the new range. On the 21.5-inch iMacs you can order a 1TB Fusion Drive. On the 27-inch iMacs you can configure a 1TB Fusion Drive for £200 or 3TB for an extra £320. There’s also a 768GB Flash storage option on the larger iMac. This will be even faster than the Fusion Drive but is smaller in capacity and will set you back nearly as much as the Mac itself, at an extra £1,040.

New iMac: In the box

All the new iMacs comes with an Apple Wireless Keyboard and Magic Mouse. When you buy the new iMac you can swap out the Magic Mouse for a Magic Trackpad at no extra cost, or add the Trackpad for £59. If you hate having to charge batteries you can even opt for a wired Apple Mighty Mouse. We recommend you also purchase an Apple Battery Charger to keep the keyboard and mouse charges at all times.

A screen-cleaning cloth is also included in the box.

As usual with Apple products there’s not much in the way of documentation or manuals, although you do get a little 18-page Quick Start Guide.