Computing stuff tied to the physical world

Tuesday Teardown

In Hardware on Mar 6, 2012 at 00:01

Welcome to a new initiative on this weblog: a weekly series about taking something “interesting” apart and peeking under the hood. I’m calling it the Tuesday Teardown series, and since they’ll all be tagged “Teardown”, that link you see will bring up all posts, accumulating as we walk down this path.

The idea is to look at some neat existing technology and find out how things were engineered, which is after all often a highly creative process, reflecting the outcome of a lot of problem-solving and deep insight about the design and production of all sorts of products. Since this weblog is all about creativity, technology, and exploration, it seemed like an obvious fit to look at how “stuff” was made.

This series of posts is also a departure in that I’ll be passing the microphone to guests once in a while. There is plenty of technology – both excellent and awful – to be able to keep this weekly topic alive for a long time… if you have suggestions, would like to contribute a complete story, or simply want me to translate or do part of the writing for you – please get in touch!

To start off, here’s a little dive into an amazing piece of engineering: a vintage-2005 Apple Power Mac G5 (2x 2.5 GHz PowerPC, each dual-core), which a friend and I recently took apart, after it had suffered a catastrophic breakdown – as you’ll see.

Here’s the shiny new Power Mac, as presented in the marketing brochures (it’s about 50x50x20 cm):

Powermac g5       Overview featurette expansion 20100727

The interesting bit is that at the time, these CPU’s were hitting the limits of personal computer cooling capabilities, yet Apple wanted to really keep noise levels down. As a result, an elaborate set of cooling zones was created, each with quiet cooling fans operating independently and adapting to demands.

I wasn’t really interested in the top part (drive bays and expansion slots), or the middle part (motherboard and memory expansion). I wanted to see the CPU cooling solution:

DSC 2923

This is an oblique top view of the cooling unit, sitting on top the two CPU boards – which are separate from the big motherboard (no doubt easier to service and upgrade this way). The whole unit looks and behaves like a mini car radiator, and indeed, it uses what seems to be the same sort of thick blue-ish liquid coolant (glycol) as you’d put in your car (or your fridge, as cooling blocks).

The whole Power Mac can draw over half a kilowatt, and no doubt quite a bit of that goes to these CPU’s when maxed out. Since all of it ends up as heat, this really is an impressive feat of engineering.

Trouble is… after a few years, things tended to fail. In a pretty ugly way, in this case:

DSC 2927

Massive leakage. Taking the board with it, to the point where the solder joints got corroded:

DSC 2926

Interesting detail – look at the immense number of capacitors on there. Here’s the other side:

DSC 2925

Oh, and this isn’t a run-of-the-mill double-layer PCB either – check it out:

DSC 2930

Even 7 years later, “awesome” only barely covers the level of engineering that must have gone into this.

PS. I also extracted the power supply, rated 600W, to see whether that could be re-used at JeeLabs somehow. But the PSU didn’t really like me – my first attempt at powering it up beyond the default standby state produced fireworks inside and a smelly puff of smoke. It probably needed a certain load to function properly. Oh well.

  1. Liquid cooling in a consumer machine, wow! Having seen that I rather understand the price of the Mac Pro back in those days (beyond Apple being greedy of course!).

    Oh, and one other thing, tear-downs shouldn’t just be for Tuesdays, any day is a good day to take things apart – preferably something you don’t actually need to use the next day though :-)

    The latter point is something I often overlook, so if you don’t mind I must take my leave and put my phone back together!

  2. You link to the wikipedia article for propylene glycol, but isn’t it ethylene glycol which is used in cars?

    • Good point. Actually ethylene glycol is toxic; propylene glycol is phasing in for general coolants and is mandatory for anything associated with food (like those cooling bricks in the freezer or in the double skin tanks used for industrial-level wine fermentation).

      Of course, it is more expensive….

    • Hmm… to be honest, I don’t know which it is, so I’ve decided to remove the link altogether.

  3. I’m not sure of the timeline – but perhaps Apple legitimised advanced cooling techniques in consumer electronics.
    Teardown a modern laptop of reasonable horsepower and you will find an integrated heatpipe-style cooler. 90′s space technology spinoff.

  4. I prefer your method of “teardowns” of only examining the interesting parts, but in greater detail. Looking forward to the following posts.

  5. Wow, the damage is impressive! I wonder why they couldn’t have used something non-corrosive in their cooling system.

    • Marketing driving the required performance level, and engineers bending over backwards to get the resulting amount of heat out of the way? The PowerPC G5s were no doubt competing with high end Intel CPU’s at the time.

  6. I think you deserve the following achievement badge:

    https://www.adafruit.com/badges/5

    :)

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