My old PowerMac G5 2x2.5 GHz finally gave up the ghost late in December 2008 after a long illness. It was a bit slow with Aperture but otherwise satisfactory in every respect and I was quite troubled to have to replace it. The first problem is that pro specs Apple computers have such brilliant hardware, you can’t imagine just throwing them away. They are everything but consumable. Second was that the Mac Pro range available in December 2008 had been around for more than 18 months and was due for an imminent, but elusive, upgrade.

I tried to make do by connecting my MacBook to my 30” screen (it takes an expensive adapter and doesn’t work very well) and waited. In March, Apple announced its Nehalem range of MacPros and I ordered one the next day. Three weeks later (!) I received my 8 cores 2.66GHz MacPro.

It took me twenty four hours to order the computer because, untypically, I got scared by the prices and decided to carefully analyse my purchase.

It is common for most manufacturers to make you pay for the last few percents of performance. Look at the range of engines for a given Mercedes Benz model and you’ll see what I mean. In this case however, the 9% increase from 2.66 GHz to 2.93 GHz represented a 29% increase in price. The difference between the 2.26GHz 8 cores and the 2.93 GHz is 30% in speed and 80% in price. Sorry? Eighty Percent? Remember that processor speed is only one of the factors in general computer speed and that bigger gains can be made by adding lots of RAM (when supported) and much bigger gains by using fast disks.

So I thought about it a lot and consulted every resource available on the very new systems. I learned a few surprising things on the way and decided to save £1000 on the computer itself to spend on other things.

While I would love an extremely fast mass storage system, I need 5 or 6 Terabytes online so had to look at large hard disks rather than fast. I bought the Mac with a 1 TB Western Digital as standard, added another one and filled the last slots with two of the newer 2 TB Western Digital Caviar Green which I linked with software RAID to speed them up a bit. The new MacPros have a very clever SATA connection built into the motherboard for all the hard disks. It simplifies the hardware and, quite brilliantly, can be taken over by a Hardware RAID PCIe card which allows you to connect SAS disks in the same slots. Unfortunately, it has been discovered that the overall throughput of the whole interface is about 750MBS so anybody wanting to break records with Solid State Disks will have to do it outside the box.

I use the boot 1TB disk for all applications, put most of my data and edited pictures in the second 1TB disk and keep the whole library of RAW images in the striped RAID 0 array of 2TB disks. I know the associated risks and now use my 4 x 1.5TB Drobo as backup.

I like to have as much of my hardware as possible inside one box so I put an LG Blu Ray rewriter in the second SATA optical drive bay and added a Sonnet 4xUSB 2.0 ports PCIe card to the computer. I will eventually add a second card with 2xUSB and 2xFW400 so I have about all the ports I can use inside the computer. I am not sure I understand why Apple puts so many ports in the front of the computer as it is much too large to put on a desk and anything connected to the front would create a lot of cable clutter. I need lots of peripherals but I like my desk clean and neatly organised.

Though Apple provided 8 RAM slots, the system is much faster if DIMMS are installed in groups of 3, 6 being optimal. The practical maximum, using rare and expensive 4GB DIMMS, is therefore 24GB. Pushing up to 32GB would mean a 50% drop in pure RAM throughput and the trade-off needs to be carefully analysed.

As it is, the 6GB that come with the computer are both fast and sufficient as very few applications will take advantage of all that space. When Apple releases System 10.6 and, more importantly, 64 bits Pro Applications, the extra RAM will make quite a difference. One hopes that prices will have become reasonable by then. As it stands, getting the optimal 24GB is a £2,000 to £4,000 option depending on the source.

A good bit is the new processor tray which regroups CPUs and DIMM slots and is easily removable, making memory replacement extremely easy. Am I the only one in thinking that tray would make the Mac Pro extremely easy to upgrade? Just swap the processor daughterboard with a faster one. No news on that possibility at this stage though.

I thought I would have to wait for Snow Leopard, the advanced System 10.6 for Aperture to take advantage of the 16 available threads in the dual Nehalem processors but was quite surprised to see all of them peak in the activity monitor every time I loaded a RAW image. Aperture is certainly processor hungry and already heavily multi-threaded so buying more cores will make an immediate difference. We will see if other advances in 10.6 will make it use the new systems even better. I do hope so.

I can’t say much about the ATI Radeon HD 4870 video card apart from the slightly annoying fact that it comes with one DVi port and one Mini DisplayPort, limiting its use with today’s Cinema Displays. Again, we will see if Snow Leopard does anything interesting with it, like play Blu Ray movies..

In use, of course, the system is much snappier than the old PowerMac and Aperture has become a much more fluent tool. While 21MP RAWs still take about three seconds to load, almost all the adjustments are instant, some fluid enough to be called real-time. I still notice the gradual slowing down over time that shows that Aperture either has an unresolved memory leak or very bad garbage collection management. As it loads much faster, restarting it once in a while to alleviate the problem is less of a chore than it used to be.

My favourite thing with the new system however is how silent it is compared with the PowerMac G5 and its 9 (count them!) fans.

All this has seriously impressed on me the bottleneck that mass storage represents today. SSDs will make a difference soon but they are very poorly supported in the Nehalem MacPro with its bandwidth limited backplane. The best way to integrate them to such a machine would be as a RAID array on top of a PCIe card. This could easily reach throughputs above 1TBS without having to be too expensive as 100GB is perfectly adequate for the System and all the Applications you can put on a Mac. Will it see the light of day?