Comparing the old iMacs with today's new models


Earlier today, Apple updated the iMac line with Thunderbolt, quad-core processors across the line and a HD camera for FaceTime. Prices start at US$1,199 for the 21.5", 2.5 GHz model and climb to $1,999 for the big daddy. How do the specs compare to the previous models? Here are some of the highlights.


There are still two basic models: 21.5" and 27". Each starts with two configurations, beginning with the processor. As of January 2010, the 21.5" model sold with a 3.06 GHz Intel Core i3 or a 3.2 GHz Intel Core i3, while the 27" model featured either a 3.2 GHz Intel Core i3 or a 2.8 GHz Intel Core i5.

Today, the 21.5" machine offers either a 2.5 GHz Quad-Core Intel Core i5 or a 2.7 GHz Quad-Core Intel Core i5, while the 27" iMac features a 2.7 GHz Quad-Core Intel Core i5 or a 3.1 GHz Quad-Core Intel Core i5. That's the first time quad-core has been available across the entire iMac line. (The previous 27" model had an i7 build-to-order option, but that processor wasn't the current Sandy Bridge variety.)

Additionally, the previous models featured a 3 MB shared L2 cache, with a build-to-order 8 MB shared L3 cache option for the 27" iMac. Current models feature a 6 MB on-chip shared L3 cache across the board.


The display resolution is the same as it's been. The current options are 1920 x 1080 pixel resolution for the 21.5" model and 2650 x 1440 pixel resolution for the 27" iMac.

Apple notes that the current iMac displays feature "in-plane switching," or IPS. Originally designed by Hitachi in 1996, IPS improves color and contrast at sharp viewing angles.


Current models all start with 4 GB of RAM, just as previous models did. The current 21.5" models are upgradable to 8 GB of 1333MHz DDR3 SDRAM from Apple, while the 27" models can house up to 16 GB of the same.


Previous models featured either a NVIDIA GeForce 9400M or an ATI Radeon HD 4670 with 256 MB on the 21.5" model, while the 27" model offered the ATI Radeon HD 4670 or an ATI Radeon HD 4850 with 512 MB.

The new iMacs are clearly improved. The base 21.5" model sports either an AMD Radeon HD 6750M with 512 MB or an AMD Radeon HD 6770M with 512 MB, while the 27" starts with either that same Radeon 6770M or an AMD Radeon HD 6970M with 1 GB.

All this at the same price points. The new iMac line is clearly compelling. Maybe I'll finally replace my long-suffering G4.