Review: Custom iMac 27-inch i7

Apple's 27-inch iMac offers a number of upgrade options. Photo / Supplied

I recently got to test a friend's brand new, 'pimped' iMac i7.

Her new Mac is a top-of-the-line 2.93GHz with the bigger 2TB traditional-style hard drive fitted (not the SSD) and 12GB RAM. It took seven days to arrive once ordered, outfitted and shipped direct from China. You can track these purchases online as they approach.

A Magic Mouse and Magic Trackpad combination was added for another $122 via Apple's online Build To Order - total retail with the new GST for this setup is $4402.02.

It was ordered with 4GB RAM to save money - the buyer got some approved third party 1333MHz DDR3 RAM and put that in the other two slots (of four) for another $500 or so.

It's a five-minute job and the booklet that comes with the Mac tells you how to do it. The hardest things are: do you have the right Phillips No2 screwdriver? You need this to get the access panel off. And you have to be a bit brave, if you've never done it before, to press the RAM home properly.

All good. The configurator on the Apple site lets you pick 4GB (2x2GB) RAM, or 8GB (4x2GB) for another $399, or 2x4GB for an extra $818, or the max of 16GB for 4x4GB RAM SODIMMs for an extra $2044, so you can see why it was sensible to order the stock RAM, leaving two slots free.

If the buyer ever wants another speedup, she can buy another 2x4 GBs at some point to replace the 2x2s with.

An odd thing about OS X Snow Leopard is that it can run 64-bit native, but defaults to 32-bit. You can boot it into 64 by holding the 6 and 4 keys down on startup.

This is nuts! So I downloaded a little free app called K64Enabler which makes it boot 64-bit on every startup. This is much better for this Mac, as it will be used for massive Photoshop composites.

To tell what mode you are running, open About This Mac in the Apple menu then click on More Info..., you get System Profiler. Click on the Software parent tab on the left, and you will see a line on the right that says "64-bit Kernel and Extensions:__" - the last part will either say Yes or No.

If you have more than 4GBs of RAM, a late model Mac (including the laptops) and you intend to use Photoshop, Logic or Final Cut, I strongly recommend running in 64-bit mode, which can give you 250 per cent faster system call entry and 70 per cent faster user/kernel memory copy.

OK, how fast is the result? This model of iMac beat the last generation of Mac Pro towers when it first came out a couple of months ago in some tests. So Apple almost immediately brought out all-new Mac Pros to compensate ... these can now hit about three times the performance of this iMac, but cost thousands more.

I used two tests, Geekbench (the 64-bit version) and Cinebench. The beauty of these two apps is that they deliver figures meaningful for any computer: Mac, iDevice, PC, Linux or Solaris. Geekbench comes with both 32-bit and 64-bit versions. Cinebench concentrates on video performance and the speedup multiprocessing gives, while Geekbench concentrates on CPU.

I used a three-year-old 20-inch 2GHz Core 2 Duo with 3GBs RAM as a benchmark. This CPU, at different speeds, still powers the MacBook, the 13-inch MacBook Pro and the Mac mini, but has recently been joined by Intel's Core i3, i5 and i7 in Apple's PCs.

The three-year-old clocked an overall Geekbench score of 2877.

A six-month-old 13-inch MacBook Pro with the same chip running at 2.66GHz was a lot faster, at 3963. This has a 1.06GHz bus instead of an 800MHz bus, and 4GB RAM.

The i7 iMac clocked 10,850. Adding an SSD (still prohibitively expensive, to my mind) would improve this score.

I don't want to throw too many numbers at you, but the three-year-old iMac Geekbench sections compared to the new i7 come out at: Integer Section 2340/9566; Floating Point Section 4148/16,948; Memory Section 2137/5473; and Stream Section 1791/5473. So it's roughly four times faster on most counts.

You can read more about what all this means at the Geekbench site. It even has an iPhone app so you can clock your iDevice (my new iPhone 4's overall score is 371).

PrimateLabs has a section that lets you compare Mac results to all sorts of other results, by the way.

How about video? The new iMac range comes with three video card options. The 21.5-inch models have either an 13 dual-core or i5 quad-core processor, teamed with an ATI Radeon HD 4670 graphics processor with 256MB of video RAM, or an ATI Radeon HD 5670 graphics processor with 512MB VRAM respectively.

The bigger 27-inch model comes with an i5 teamed with an ATI Radeon HD 5670 graphics processor/512MB VRAM, or as the also quad-core but more powerful i7 Intel processor.

The i7 27-inch - as per that tested - gets the same ATI Radeon HD 5750 graphics processor, but it has a whopping 1GB of GDDR5 memory.

This is where Cinebench comes in. That older Core 2 Duo achieves a 5.36 frames per second OpenGL rating, a 1.11-point CPU rating, .57 points for a single CPU and a multiprocessor ratio of 1.94 times.

The new 27-inch gets an OpenGL score of 34.99fps, 5.45 points CPU, 1,19 pots for a single core and a multiprocessor ratio of 4.61x.

On the Cinebench site, the 2.8GHz i7 scores 32.26 overall from its four-core/8-thread i7 CPU and ATI Radeon 5750 video card , and it's pipped by the kind of cards PC gamers get to enjoy - examples are an 8-core 16-thread 3.33GHz Quadro FX 5800/PCI/SSE2 (Cinebench 45.52) and by the 12-core 2.62GHz ATI FirePro V8750 (FireGL) with a Cinebench score of 48.73.

So as usual, you can well and truly beat these iMacs with PCs, but for Mac fans, the new i7 iMac offers outstanding performance.

You can see a lot more speed tests and comparisons at the BareFeats site.

(If there are any specific timings you'd like me to try, let me know in the comments.)

- Mark Webster mac-nz.com