Spring is here, and after a near-eternity of scraping the barrel of recession, there is more work about. Can you squeeze more from your existing Mac, or must you replace it?
Few Macs are designed to be upgraded much, but in skilled hands most can be tweaked to deliver better performance. The end result is unlikely to match that of an equivalent new Mac, but if you need to control your cash flow, upgrading can buy you time until you can afford better.
Scope and Memory
The first thing to establish is the scope for upgrading your current Mac. Even if you still have its original hardware specification provided by Apple, you should download the authoritative Mactracker app from here, which gives hardware and software details for every model ever sold.
It is quite common for the maximum memory capacity quoted by Apple to have increased, as newer memory modules have become available. However if your late 2006 MacBook Pro 17” Core 2 Duo already has 4 GB installed, and you need to be running Yosemite, then no amount of money spent on it will help: it can only access 3 GB, and can run no version of OS X more recent than 10.7.5.
If you can install sufficient memory and run the version of OS X that you need, you next need to look at storage space. Very few Macs cannot have their internal hard disks replaced with something much more capacious and faster, and most desktop models are designed with this in mind.
Mactracker informs you of the hard drive interface, whether it is parallel or serial ATA (PATA or SATA) and its performance standard (e.g. 6 Gbps), but you will also need to know the form factor of the drive bay. The latter defaults to 3.5” for most desktop systems, and 2.5” for laptops and the Mac mini; if you are in doubt, check with Mac Upgrades, VIS, or The Bookyard, or by looking up the model of the hard disk shown in Disk Utility. Some more recent iMacs also have a second 2.5” drive bay, intended for an SSD, and Mac Pro models offer four full-size 3.5” bays.
You may see substantial gains in performance by replacing a conventional internal hard disk with an SSD; disk-bound apps, whose performance is primarily limited by disk access, should benefit most. As SSDs are most commonly provided in 2.5” format, you may need an adaptor to do this properly, and dealers specialising in upgrades should offer this or other adaptors if you explain to them which model you wish to upgrade. Those and installation kits to support the second 2.5” bay in iMacs should cost around £20.
The biggest disadvantage with SSDs is their cost, so you could find yourself having to add a large external drive on which to store some applications and most documents.
Graphics cards are often ignored when upgrading, but with recent versions of OS X making increasing use of them to run number-intensive calculations, this could leave you with a highly capable but slow Mac.
The scope for improving your graphics card is the most limited, as they have to match the exact model of Mac precisely. Although Mactracker may list several optional graphics cards for iMacs, for example, they are closely tied to the motherboard and you are most unlikely to be able to upgrade yours. In practice the only systems which you are likely to be able to improve are Mac Pros, and even then you must buy a card specific to your model.
When you cost up each upgrade option, remember that some will need to be performed by an engineer, and all will incur some downtime. Ensure that your preferred route addresses as many of the shortcomings of your current hardware as possible: there is little benefit to having vast amounts of free disk space if you still have to go to lunch when rendering even a short video clip.
Tools: Finding the Bottleneck
If you use the front-line utility for monitoring performance, Activity Monitor, it is all too tempting to assume that throwing loads of memory into your Mac will solve all its problems. Although OS X does love lots of physical memory, you need to develop a better feel for the bottlenecks that constrain your everyday work, rather than getting alarmed at how much memory apps seem to use. OS X has sophisticated memory management which tries to make the best use of the hardware that is available, so it should be no surprise if it is doing just that.
Yosemite’s improved Activity Monitor is much better, and allows you to work out what those apps are taking time to do. In many cases, you will see that key tasks are disk-bound, in which case a capacious SSD might work a treat, or are being stifled by a slow Internet connection. Although your processor will have two or more cores, monolithic apps can still hog one and would only then benefit from greater processor speed.
Unfortunately there is no tool that can reveal how older and slower internal system buses effect performance: the only way to improve those is with a newer, faster Mac.
Updated from the original, which was first published in MacUser volume 30 issue 03, 2014.