Lab Tested: New 27-inch iMac speed results

Finally, after many phone calls to many Apple Stores—as well as a few heartbreakingly fruitless trips to far-flung retail stores—the hard-to-get 27-inch iMacs are in our lab and tested. The results, however, were not what we expected.

The new 27-inch iMacs are available in two standard configurations. Both have 8GB of RAM and feature Intel’s quad core Ivy Bridge processors. The $1999 model sports a 3.2GHz Core i5, while the $1799 model uses a 2.9GHz Core i5.

Both iMacs include 7200-rpm, 1TB SATA-3 hard drives, but the drives in these two iMacs we received are not identical—and neither were their performance scores. Our $1999 iMac has a Western Digital WD10EALX Caviar Blue drive with 32MB of cache. Our $1799 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 $1799 iMac was 34 percent faster than the $1999 iMac in the 2GB folder copy test, and 20 percent faster when uncompressing a 6GB file. In fact, the $1799 iMac was faster than the $1999 iMac in nine of the 15 tests that make up our Speedmark 8 benchmark suite. The $1799 iMac had an overall Speedmark 8 score that is 6 percent higher than the $1999 iMac.

As a reality check, I ran Blackmagic’s Disk Speed Test, using the 5GB file settings. I 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 $1799 iMac took 96 seconds to copy a 6GB file from one part of the drive to another, while the WD drive in the $1999 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 $1999 iMac, it was faster than the $1799 iMac in both the Cinebench CPU test (7 percent faster) and MathematicaMark (5 percent faster). The $1999 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 $1799 iMac 2012 was 28 percent faster overall than its predecessor, a 2.7GHz Sandy Bridge quad-core Core i5 system. The new $1799 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 $1799 model, and an Nvidia GeForce GTX 675MX with 1GB GDDR5 memory in the $1999 model. (The $1999 iMac can be upgraded to 2GB of video memory for an additional $150.) 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 $1999 iMac, and 11 percent faster on the $1799 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 $1999 iMac, and 32 percent faster than the $1799 iMac. The Core i7’s Hyper Threading helped the custom iMac post Cinebench CPU scores that were 24 percent faster than the $1999 iMac and 29 percent faster scores than the $1799 27-inch iMac.

Check back soon for Macworld’s full review of the new 27-inch iMacs. You can also read our review of the 21-inch iMacs (Late 2012).