May 04, 2011, 10:16 AM — On Tuesday, Apple released an updated line of iMacs, featuring quad-core Sandy Bridge Intel processors and Thunderbolt ports. Macworld Lab has all four standard configuration models, and the results for the $1999 27-inch iMac are in. The results do not disappoint, with the new iMac besting the previous generation of standard-configuration iMacs. The new 3.1GHz iMac even bested the performance of some impressively-equipped build-to-order models we've tested previously.
The $1999 iMac was the first to arrive in our lab and the first to be tested. At the heart of this iMac is a 3.1GHz Core i5 quad-core processor. This iMac also has a 1TB 7200-rpm hard drive, and AMD Radeon HD 6970M graphics with 1GB of video memory.
Our overall system performance test suite, Speedmark 6.5, shows the new system to be 16% faster than the previous high-end standard configuration iMac, a 27-inch 2.8GHz Core i5 quad-core model with a 1TB 7,200-rpm hard drive, and ATI Radeon HD 5750 graphics with 1GB of dedicated RAM. (Apple considered the older 27-inch 2.8GHz Core i5 iMac a BTO option, but the online Apple Store didn't treat it like one, so we decided to treat it like a standard configuration model.)
In our iTunes encode test, the new iMac was 22% faster than the 27-inch 2.8GHz Core i5 iMac. The new iMac was also 18% faster in our Handbrake test, 20% faster in the Cinebench graphics test, 21% faster in the Cinebench CPU test, and 16% faster in our MathematicaMark tests.
Like the older 27-inch 2.8GHz Core i5 iMac, all of the new standard-configuration iMacs support Turbo Boost, which can give more processing power to individual cores when needed. And also like the older 27-inch 2.8GHz Core i5 iMac, all of the new standard-configuration iMacs don't have Hyper Threading, a technology that presents the OS with two virtual cores for each physical core.
Comparing the new system to last year's BTO models, we see less of a difference in performance. Just two Speedmark points separate the new 3.1GHz Core i5 iMac from the 2.93GHz Core i7 quad-core BTO iMac. The 2.93GHz model, like all 2010 iMacs, does not use Sandy Bridge processors, but it does support both Hyper Threading and Turbo Boost. In applications such as Cinebench and MathematicaMark, which can take advantage of eight virtual cores, the 2.93GHz BTO iMac outperformed the new 3.1GHz iMac.