PlasmaBlog

I have been using a MacBook Air as my sole laptop for a month or so now. In general I feel very positive about my experience with it. However, there is one issue that seems to be plaguing myself and other MacBook Air owners. When taxing the CPU for extended periods, the MacBook Air shuts down one of it’s cores to prevent overheating. The easiest way to reproduce the problem is to watch a few YouTube videos. After approximately 15 minutes the Mac OS X Activity Monitor clearly shows only one core running. Within a few minutes of the CPU load being lightened, the dormant core springs back to life.

While running on only one CPU core, the MacBook Air is barely usable. The UI becomes jittery and the onscreen trackpad pointer jumps around.

While trying to find a solution to the problem I came across this forum post. The author suggests an application called ‘Coolbook‘ which purports to underclock the laptops CPU by lowering the voltage supplied to the processor and by more agressively throttling the speed of the CPU. My initial reaction was one of extreme skepticism. Alarm bells were ringing. While I consider myself a geek I have never dabbled with overclocking of CPU’s and have never even heard of underclocking. But after reading five pages of positive responses I decided to take the plunge and install ‘Coolbook’.

Firstly, let’s describe the applications UI as abysmal. There is no getting away from it. Maybe it would make more sense to someone with experience in underclocking but the whole point in a GUI is to assist the uninitiated in achieving their goals without having to resort to technical manuals. Needless to say I had to resort to the manual which is thankfully quite good.

After tinkering with the various parameters and following the advice of others on the forum I settled on the following settings…

When power adaptor is plugged in…

600HMz = 0.9V
800MHz = 0.9V
1200MHz = 0.9V
1400Mhz = 0.9V
1600Mhz = 0.95V

When the MacBook is running on battery…

600MHz = 0.9V
800Mhz = 0.9V
1200Mhz = 0.9V

This lowers the voltage supplied to the CPU by 0.2V. Also of note is the removal of the 1400MHz and 1600MHz setting when running on batteries. This has had the following results…

Before Coolbook

Approx CPU temperature under light load 52C
Approx CPU temperature under heavy load 75C
Fan speed under light load 2500rpm
Fan speed under heavy load 6500rpm
Battery life under light load - 3.35

After Coolbook

Approx CPU temperature under light load 43C
Approx CPU temperature under heavy load 62C
Fan speed under light load 2500rpm
Fan speed under heavy load 4250rpm
Battery life under light load - 4.25

Since installing Coolbook, my MacBook Air has suffered no core shutdowns, it has run significantly cooler to the touch, it is quieter (as a result of the lower fan speeds) and it lasts almost an hour longer than usual when running on battery power. As of yet I have found no downsides and I have not experienced any instability.

There is some debate about the possibilities of damaging the CPU by underclocking it. My research leads me to believe that such damage is unlikely and that using too low a voltage will simply result in OS instability. However, I am not advising anyone else rushes into underclocking their MacBook Air. All I offer is my experience with ‘Coolbook‘ for those who might be interested I will update this post should my experience change over the coming weeks.

The MacBook Air is the latest in a long line of Apple notebooks to find a home at ‘Chez Randtoul’. Until its arrival I had considered the MacBook Pro to be the gold standard for build quality in a notebook. However, there are a few issues with the MacBook Pro, caused by less-than-perfect design.

1) When closed the screen touches the keys. Over time this leaves permanent marks on the display. Ultimately caused by a lack of clearance between the screen and keyboard, the problem is exasperated by the amount of flex in the lid. Apple has made modifications to the MacBook Pro/Powerbook over the years to try and address the issue (mainly through the addition of rubber pads around the screen bezel). A number of third party solutions have also sprung up, including screen protecting microfiber cloths that are placed on the keyboard before the lid is closed. However, in my mind these are band-aids developed to mask a fundamental design flaw.

2) While the casing for the MacBook Pro is beautifully anodized aluminum, the bevelled edge just below the space bar is painted. Whether this becomes a problem for the user depends heavily on how they type, and where they rest their thumbs. If, like me your thumbs tend to sit on the space bar, over time the painted area can become discolored and eventually wear off altogether, revealing the bare aluminum underneath.

3) Under certain circumstances the backlighting of the keyboard can actually make the keys more difficult to read. Since the death of the Titanium Powerbook, Apple have chosen to match the color of the keys to the notebooks casing, resulting in a light grey keyboard on the Macbook Pros. During daylight this is fine (light grey keys, black characters). During darkness (once the backlighting is activated) again all is well (black keys, white characters). But in a room with a low light the result is white characters on light grey keys. While not too much of a problem for touch typists, the low contrast between the keys and characters tends to negate the supposed benefits of a backlit keyboard.

Back to the MacBook Air. There has of course been much debate about its merits since it’s launch. However, what cannot be denied is it’s exceptional build quality. The curved surfaces of the casing give the notebook an amazing amount of rigidity, especially when the ultra-thin form factor is taking into consideration. Indeed, I have heard many people comment that the MacBook Air feels as though it is carved from a solid slab of aluminum.

Stanley Kubrick once said “Sometimes the truth of a thing is not so much in the think of it, as in the feel of it.“

While the MacBook Air feature set is a lesson in compromise and sacrifice, the ‘feel’ of the Air is of undeniable quality and craftsmanship.

So what about those three design flaws still present in the Air’s big brother, the Macbook Pro?

1) The keys no longer touch the screen. This has been achieved by making three changes. Firstly a rubber bumper now runs around the entire circumference of the screen. Secondly, the use of the MacBooks chiclet style recessed and flat-surface keyboard results in more clearance between the screen and keys. Thirdly, the curves of the lids casing provide much more rigidity, resulting in less screen flex.

2) There are no painted areas. While I haven’t taken a sheet of sandpaper to my new MacBook Air, I have given it a thorough inspection and it appears that all surfaces are anodized aluminum.

3) The keyboard is now black. While this is cosmetically a little jarring for some (although it brings back fond memories of the Titanium Powerbook for me), it provides high contrast between the keys and characters under all lighting conditions. Is this a rare case of Apple choosing function over form? Surely not
After two weeks with my MacBook Air I find it difficult to levy any significant criticism of the units build quality and engineering. It truly is the gold standard of notebook design. Alas poor MacBook Pro. I knew him well.