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Bevy of noteworthy upgrades in new iMac

The new iMac has plenty under the hood to drool over, including unannounced Intel silicon and a slot for a solid-state cache drive, according to iFixit.

Brooke Crothers Former CNET contributor
Brooke Crothers writes about mobile computer systems, including laptops, tablets, smartphones: how they define the computing experience and the hardware that makes them tick. He has served as an editor at large at CNET News and a contributing reporter to The New York Times' Bits and Technology sections. His interest in things small began when living in Tokyo in a very small apartment for a very long time.
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Brooke Crothers
3 min read

The iconic iMac aluminum enclosure houses a bevy of noteworthy upgrades, including Intel's and Advanced Micro Devices' latest silicon and the latest Intel-Apple interface, as iFixit's teardown of the 21.5-inch iMac ably reveals.

Let's look at a below-the-radar item first since there's already been plenty of ink devoted to the marquee features.

There is a Starship Enterprise-esque look to the main logic board, as iFixit points out. And the gleaming copper heat pipes add an interesting aesthetic to a purely functional layout.
There is a Starship Enterprise-esque look to the main logic board, as iFixit points out. And the gleaming copper heat pipes add an interesting aesthetic to a purely functional layout. iFixit

Intel Z68 chipset: This is Intel's freshly minted chipset. New enough that you won't find it--at least not prominently--on Intel's Website because it hasn't been officially released. The Z68 supports SSD caching: that is, using a relatively small-capacity, solid-state drive as a "cache" for a larger magnetic hard disk drive (see photo below). Interestingly, this SSD-HDD configuration is widely used in transaction-heavy businesses such as banks, where the top of the storage pyramid is composed of SSDs that act as a cache for the larger-capacity, and slower, magnetic drives.

Intel, in fact, is expected to bring out SSDs targeted specially at this kind of application.

The area--which is under the Sony Optiarc optical drive--shaded in red is 'presumably' where the optional SSD is housed, according to iFixit.
The area--which is under the Sony Optiarc optical drive--shaded in red is 'presumably' where the optional SSD is housed, according to iFixit. iFixit

Intel desktop-class Sandy Bridge processors: In the model torn down by iFixit, the processor is a 2.5GHz quad-core Sandy Bridge Intel Core i5-2400S. This is a pure 32-nanometer processor (previous-generation Intel silicon with graphics integrated into the same chip package was a 50-50 split, the processor was 32nm but the graphics was 45nm).

Other i5-2400s goodies include a decent clock speed of 2.7GHz, which overclocks (what Intel calls Turbo Boost) to 3.7GHz, a 6MB cache, and 65-watt thermal envelope, which is respectably low for a high-performance quad-core desktop-class chip with built-in graphics.

Though not a critical issue for desktop jockeys because of the use of discrete AMD HD 6000 series graphics, it is nevertheless interesting to note that Intel's desktop Sandy Bridge silicon has lower-performance HD 2000 integrated graphics compared with its HD 3000 mobile counterpart.

But don't take my word for it, here's what Intel says: "The primary difference between Intel HD Graphics 2000 and Intel HD Graphics 3000 is the number of execution units contained in the processor. Intel HD Graphics 2000 contains six execution units, and Intel HD Graphics 3000 contains 12 execution units. This means that Intel HD Graphics 3000 is better suited for more graphics intensive applications such as those that use 3D."

AMD graphics processor: Which leads to AMD's Radeon HD 6750M GPU. This is paired with four Hynix 1Gb GDDR5 SDRAM chips (totaling 512 MB), according to iFixit. A lot has been written about this graphics processing unit, so suffice to say that it integrates 480 Stream Processing Units and 24 Texture Units, according to AMD's spec page. Also of note is an engine clock speed of 500MHz-725MHz, and processing power (single precision) of 480-696 GigaFLOPS.

And note that higher-performance Radeon HD 6770M or Radeon 6970M graphics cards are offered on higher-end iMacs.

AMD's Radeon HD 6750M GPU with four Hynix memory chips.
AMD's Radeon HD 6750M GPU with four Hynix memory chips. iFixit

Other components worth mentioning include a Broadcom BCM57765B0KMLG Integrated Gigabit Ethernet and Memory Card Reader Controller, a Cirrus 4206BCNZ audio controller, and Intel L102IA84 EFL Thunderbolt port chip.

Thunderbolt: The merits of Thunderbolt have been written about ad nauseam. In brief, the new connection technology combines high-speed data transfer and high-definition video on a single cable. Running at 10Gbps, Thunderbolt can, theoretically, transfer a full-length HD movie in less than 30 seconds. The new iMac has two of these ports. Because Thunderbolt can act as a video port, it will allow you to connect two additional monitors to the iMac, according to Rich Brown, who wrote CNET Review's take on the new iMac.

Serial ATA: Finally, there's an interesting tidbit at MacFixIt, which cites a blog posting by Other World Computing. "The company mentions that the latest firmware update for the new 2011 iMacs has unlocked SATA III capabilities in the systems, allowing for up to 6Gb/sec data throughput on the internal hard drive bays. The past iMac and MacBook Pro models have shipped with SATA II drive controllers that handle up to 3Gb/sec throughput, but the new systems apparently use updated controllers," according to MacFixIt's Topher Kessler.