Benchmarks: New IMacs

Macworld Lab has been a benchmarking madhouse lately. First, the Lab tested the new Mac minis, and then there was the new 15-inch 2.66GHz MacBook Pro. Now we have benchmark results on the four new iMacs. The speed improvements over the iMacs released in April 2008 are significant, and there are also some interesting performance observations between the new iMac models.

Apple offers four standard configurations of the new iMac, three 24-inch models and only one 20-inch iMac. The iMac's Core 2 Duo processor speeds start at 2.66GHz (one 20-inch model and one 24-inch model), and include 2.93GHz and 3.06GHz. Previously, iMac processor speeds started at 2.4GHz, and included 2.66GHz, 2.8GHz, and a built-to-order 3.06GHz. The 6MB Level 2 cache in the new iMac is the same as the preceding iMac line.

The system bus is still at 1,066MHz, but now Apple uses 1,066MHz DDR3 RAM instead of the 800MHz DDR2 RAM in the previous iMac. Apple also doubled the amount of RAM in the standard configurations, with 2GB in the 2.66GHz 20-inch iMac and 4GB in the other three models. All RAM in the new iMacs are installed in pairs, leaving no open slots. The previous iMac line had 1GB in the 2.4GHz iMac, and 2GB in the 2.66GHz and 2.8GHz iMacs.

The hard drives in the standard configurations received a nice jump in capacity. Previously, the iMac had a 250GB drive in the entry-level iMac, and 320GB drives in the other models. Now, the entry-level iMac has a 320GB drive, the high-end iMac has a 1TB drive, and the two iMac models in-between have 640GB drives. All of the drives new and old are/were 7,200 rpm drives.

The iMacs no longer use ATI video cards as standard equipment. The two 2.66GHz-based iMacs use Nvidia's GeForce 9400M, which shares 256MB of memory with the CPU. The 2.93GHz iMac uses Nvidia's GeForce GT 120 and the 3.06GHz iMac uses Nvidia's GeForce GT 130; those two iMacs have 256MB and 512MB of dedicated memory, respectively.

Let's start with the fastest model, the 3.06GHz 24-inch iMac. It posted an overall Speedmark score that was 24 points (8 percent) higher than the previous 24-inch iMac with the same 3.06GHz Core 2 Duo processor (available as a built-to-order model). The new 3.06GHz iMac was also 8 seconds faster in our Photoshop Suite test, and 5 seconds faster in our Zip Archive test. The differences in our other application tests either didn't exist or were 1 to 2 seconds. The key difference between the new and old 3.06GHz iMacs is the RAM type and speed. In our Call of Duty 4 test, the new 3.06GHZ iMac's frame rate increase over the older BTO 3.06GHz iMac was insignificant--less than a full frame.

Now let's look at the entry-level model. The new entry-level 2.66GHz 20-inch iMac had a Speedmark score that was 26 points higher (11 percent) than the previous entry-level model, a 2.4GHz 20-inch iMac. The biggest speed increases with the 2.66GHz iMac in our application testing appeared in our Photoshop Suite test, Cinema 4D Render test, and our Zip Archive test. In our Call of Duty 4 test, we saw a improvement of about 4 frames per second on the 2.66GHz iMac.

The new 2.93GHz 24-inch iMac sells for $1,799, the same price (when it was released) as the old 2.8GHz 24-inch iMac (the previous top-of-the-line). The 2.93GHz iMac had a Speedmark score that was 20 points (7 percent) faster than the 2.8GHz iMac.

Interestingly, the old 2.8GHz 24-inch iMac, with its 256MB ATI Radeon HD 2600 Pro graphics card posted a Call of Duty frame rate that was faster than both the new 2.93GHz (256MB GeForce GT 120 graphics) and the 3.06GHz iMac (512MB GeForce GT 130).

Let's see how performance differs within the new iMac line, starting with the two 2.66GHz iMacs. The new 24-inch 2.66GHz iMac doesn't simply offer a bigger screen, more RAM (4GB versus 2GB), and a larger hard drive (640GB versus 320GB) than the entry-level 20-inch 2.66GHz iMac. For the extra $300, you get a performance boost, too; the 2.66GHz 24-inch iMac posted a Speedmark score that was 14 points (5 percent) more than the 2.66GHz 20-inch model. The 24-inch 2.66GHz iMac was also faster that the 20-inch 2.66GHz in our Photoshop Suite test, Compressor MPEG Encode test, iMovie HD Aged Effect test, and Zip Archive test. The 24-inch 2.66GHz iMac was 4 frames faster in our Call of Duty 4 frame rate test.

There's a $400 difference between the high-end 3.06GHz iMac and the 2.93GHz iMac. Looking at the Speedmark score, there's only an 11-point difference (4 percent) between the two iMacs. But the key difference between the two is the graphics card; the 3.06GHz iMac has a 512MB Nvidia GeForce GT 130, while the 2.93GHz iMac has a 256MB Nvidia GeForce GT 120. The 3.06GHz iMac posted about 7 more frames per second (11 percent) than the 2.93GHz iMac in our Call of Duty frame rate test.

One interesting test result comparison is with the 2.66GHz 20-inch iMac and the new $799 2GHz Mac mini with a 320GB hard drive (). Because of the lack of a matte screen option on the iMac, a Mac mini with a matte LCD of your choosing might be an option--you can easily find a 20-inch LCD with decent image quality for about $200, bringing the price of a Mac mini setup to $999 without a keyboard and mouse. But the Mac mini has slower components, including a 5,400 rpm hard drive and a 2GHz Core 2 Duo processor, as well as only 3MB of Level 2 cache. The Speedmark difference is drastic, with the 2.66GHz 20-inch iMac 54 points higher (27 percent) than the 2.0GHz Mac mini. The Call of Duty 4 test results from the 2.0GHz Mac mini are less than 2 frames slower than the 2.66GHz 20-inch iMac. Both machines use the same Nvidia GeForce 9400M graphics subsystem.

Look for a full review of the new iMacs with mouse ratings in the next few days. And stay tuned for more benchmarks--we're furiously testing the new Mac Pros.

[Roman Loyola is a senior editor for Macworld.]

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