The Bottom Line
The 2011 27-inch iMac is a compelling update. Apple dropped the original Intel Core-i processors, and moved to the latest generation of Intel's Quad-Core i5 and i7 Sandy Bridge processors. If you're updating from one of the Core-i3 iMacs, or the even older Core 2 Duo systems, the speed increases are amazing. If you're upgrading from a 2010 27-inch iMac, however, the major performance gains will be in graphics and the Thunderbolt I/O.
The 27-inch iMac is by far my favorite desktop Mac. Its huge display and all-in-one design are hard to beat.
- New Sandy Bridge-based i5 and i7 processors.
- AMD Radeon 6770M and 6970M graphics processors.
- Memory is easy to upgrade.
- Dual Thunderbolt I/O provides very high-speed interconnect.
- Best-looking all-in-one design.
- Limited upgrades.
- Hard drive isn't user-serviceable.
- 2.7 GHz and 3.1 GHz Intel Quad-Core i5 processors
- 3.4 GHz Intel Quad-Core i7 Processor (build-to-order)
- 4 GB RAM, user-expandable to 16 GB (third-party RAM up to 32 GB)
- 1 TB, 2 TB hard drives
- 256 GB Solid State Drive
- AMD Radeon HD 6770M or AMD Radeon HD 6970M graphics
- 2 Thunderbolt, 4 USB 2, FireWire 800 ports
- SDXC card slot
- AirPort 802.11a/b/g/n Bluetooth 2.1 + EDR
- Ethernet 10/100/1000
Guide Review - Spring 2011 iMac Review - Review of the 27-inch 2011 iMac
The 27-inch iMac received a generous update from Apple that brings new processors, graphics cards, memory, and I/O. That would seem to make this update more of a major upgrade, except that the iMac chassis remains fundamentally the same.
2011 iMac Processor
Apple outfitted the 2011 27-inch iMac with the all-new Sandy Bridge-based Intel processors, which are the second generation of the Core-i processors previously used in most of the Mac lineup. The Sandy Bridge processors offer a nice boost in performance. In the case of the 27-inch iMac, Apple went with 2.7 GHz or 3.1 GHz Quad-Core i5 processors for the stock models. The build-to-order version adds the choice of a 3.4 GHz Quad-Core i7.
All models of the Quad-Core i5 support Turbo Boost, which can raise the clock frequency of the processor when a single core is being used. If you spring for the Quad-Core i7 build-to-order model, the processor also supports Hyper-Threading, which allows each core to run two threads at once, making a Quad-Core i7 appear to be an 8-core processor to the Mac's operating system.
2011 iMac Graphics
The 2011 27-inch iMacs received new graphics processors; either an AMD Radeon HD 6770M or the more powerful AMD Radeon HD 6970M, depending on which processor you select. The 6770M processor includes 512 MB of dedicated graphics RAM, while the 6970M doubles that to 1 GB of graphics RAM, or 2 GB graphics RAM in the build-to-order model. Both graphics processors are a great improvement over previous iMac offerings.
As expected, Apple included the new Thunderbolt I/O capabilities in the new iMacs. The 27-inch model gains a pair of Thunderbolt ports that can be used to drive an external display, as well as to connect external peripherals, such as hard drives and video and audio gear. Having two Thunderbolt ports may be advantageous for anyone who needs high-speed I/O. The ability to dedicate one of the Thunderbolt ports to external drives and other peripherals, while leaving one available to drive external displays may be an ideal setup for the Mac professional.
Thunderbolt offers speeds up to 10 Gbps; that's a whopping increase over the FireWire 800 (786 Mbps) and USB 2 (480 Mbps) ports. Thunderbolt peripherals aren't available in great numbers yet, but by the end of this summer, I expect to see many new offerings. In the meantime, the Thunderbolt port will handily drive any external display that uses DVI, DisplayPort, Mini DisplayPort, or other digital connection systems (adapters may be required).
Apple raised the bandwidth of memory to use 1333 MHz DDR3 RAM. The iMac still has four RAM slots. The stock memory configuration is 4 GB, using two 2 GB RAM modules, which leaves two memory slots open for expansion. Apple says the iMac will support up to 8 GB of RAM, although it has already been found to easily accommodate 16 GB. The i7 version has been tested to work with 32 GB of RAM from third-party vendors.
A 1 TB hard drive is the default for the base 27-inch iMac; options include a 2 TB hard drive and a 256 GB Solid State Drive, either in place of or in addition to a hard drive. The internal hard drive isn't considered a user-serviceable part, so you should select your target hard drive size when you order your iMac.
The 27-inch iMac is a dream of a desktop Mac. Any of the configurations would be a great choice for most users. You just can't imagine how great your desktop can look until you see the gorgeous 27-inch display.
The base configuration is an excellent choice for just about anyone, but stepping up to the AMD Radeon HD 6970M will give graphics professionals the added performance they need. It's also a good choice for gaming, of course.
There have been some complaints about the hard drives in the new iMacs being slightly proprietary, keeping DIYers from being able to upgrade the drive on their own. I believe DIYers will find a way around this issue. For most iMac users, this won't be an issue at all, because by design, iMac drives were never considered a user-serviceable part.