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Apple’s new quad-core iMac — analysis

Photographers need a computer workstation, even those shooting film, because film today means scanning and Photoshop.

Apple today announced new iMacs and MacMinis. It appears that Apple will be waiting to update the Mac Pro, but how long remains to be seen.

I’ve not been a fan of previous iMacs because of limited expansion options and dual cores and limited memory, crippling its possibilities. Today Apple addressed all those issues except one: storage.

Note well that I still favor the Mac Pro for its expansion options; and it’s still a much better investment for serious work, but the new quad-core iMac closes the gap, and will therefore appeal to some users, and not without merit.

Here is my quick take on the new 27" Apple iMac—

CPU speed — go for quad-core; this is mandatory if you want good Photoshop and/or Lightroom performance now and moving forward. Also, hyperthreading works extremely well with most programs, so it is well worth the +10% cost bump to go with the 2.8GHz Intel Core i7 instead of the 2.66GHz Intel Core i7; you get a 5% faster clock speed, and you get eight virtual cores instead of four, which will serve you well over time. With the 2.8GHz Core i7, speeds should be very comparable to a Mac Pro, assuming disk I/O is not a factor.

Memory — it’s great that the iMac now has four memory slots which allow 16GB. It also means that 8GB is now inexpensive using 2GB modules, a boon for many iMac users. Your smart move is to get a 4GB kit for about $88 to add to the 4GB that comes with the iMac, try out your workflow with 8GB, then move to 16GB later if you really need it.
Getting 16GB (four 4GB modules) is a $1400 upcharge from Apple. That money buys 32GB for a Mac Pro from OWC with money left over. OWC already has a 16GB kit for the new iMac.

Storage — unless Apple has changed the design, swapping the internal hard drive will remain a horrible exercise that very few users should attempt. Get the 2TB drive option for speed and to put of the day when you need more space, because external drive speed via Firewire 800 is mediocre to poor.

Want a fast Time Machine backup, a fast external drive, a fast mirrored internal drive, a striped RAID for Photoshop? You’re out of luck with the iMac. It’s a two-legged table in terms of performance possibilities.

Storage expansion — with only one internal hard drive, you cannot increase reliability (RAID mirror) or performance (RAID stripe) internally. External storage means Firewire 800, which is slow, a problem RAID can’t solve. Worse, Firewire 800 implementation bugs mean that real world speed for writes can drop as low as 45MB/sec (especially for volumes > 1TB), about 1/3 the speed of a fast SATA drive. So this area is the Achille’s heel of the iMac. There is no option for fast external storage for the iMac.

Display — the 27" display is 2560 X 1440, the same horizontally as the Apple 30" display, but a separate 30" display is 1600 pixels high, versus 1440 for the iMac. That’s a substantial difference, and vertical is more useful. Many users will find the 27" display great for photos because more detail can be seen, but beware the high pixel density, which makes text quite small. Individuals with less than perfect eyesight might find the pixel density problematic; it’s already a bit dense on 30" displays.

Total system cost

Pleas see Total system cost. Keep things in perspective.

What does an iMac configured to play like a Mac pro cost? Assuming OWC memory and hard drives (Apple charges a premium ), here it is:

2.8GHz iMac, 16GB, 2TB apple drive: $3400 ($2449 + $950).
2.66GH Mac Pro, 16GB, 2TB + 640GB: $3330, or ~$2979 if refurbished

Some users certainly work well with 8GB, so that would drop the cost of the iMac by $700 or so, and therein lies the iMac’s appeal with its 27" display: big screen quad-core for a decent price.

But some users also have existing displays, so a Mac Pro is an easy swap. The decision is a personal one, but the Mac Pro will likely hold its value better, as well as offer future possibilities for expansion.

Hard drives and RAID

Note that with the Mac Pro configuration above, you have both a 640GB drive and a 2TB drive, so you can separate system from data. You can’t do that with an iMac internally (partitioning is the same drive), all you get get is sluggish Firewire 800, and beware > 1TB volumes which are very slow for writes, in the range of 40-50MB/sec. Bear in mind that the 2TB HItachi 7K2000 is capable of ~128MB/sec, but Firewire 800 maxes out at ~85M/sec. So a striped RAID pair on FW800 runs at about 1/3 the potential speed. In a Mac Pro, you get all the speed, ~250MB/sec. That’s a big deal for anyone whose files are large, or when total data is 500GB or more.

Other items

With the iMac you get a 27" display (2560 X 1440) not quite as large as a 30" display (2560 X 1600) for the Mac Pro, nor as accurate as top-notch displays like the NEC 30". You lose storage expansion options, you have no PCI expansion slots, one firewire port instead of four, etc. For a 30" display for a Mac Pro, you'd spend $1799, or $1400 more than for the 27" iMac. That will be very appealing from some, but personally the storage issue is far more important to me.

Protect your Mac from power surges

Either investment should be on a UPS, like the iDowell iPack; I purchased one of these recently for my second Mac Pro and it has ample power for the Mac Pro and a 30" monitor and some extras. It is also silent, something I value.

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