Cool at last.

I call my transformed iMac the Military Mac because it is so ugly that only the military could love it.

Simply stated, after replacing the nVidia 7300 graphics card with the 7600 I was no longer able to control the speed of the key fan of the three inside. The CPU fan. If you really feel the need to ask me if I connected it, please go elsewhere. That one cools the CPU, the GPU and GPU diode and the power supply. I tried a second card from ApplePalace.com with the same result, so there must be some deep seated incompatibility between the 7600 card and my 2.16gHz late-2006 C2D Intel iMac which came with the stock nVidia 7300 card. You know, the one Apple refuses to admit fries as soon as you look at it.

As earlier described here, I drilled 87 holes in the back of the iMac while it was gutted, covering them with wire mesh on the inside. These coincide with the placement of the GPU/GPU Diode radiators, the HDD and the power supply.

When I realized that I could not get the internal fan above the base speed of 1,000 rpm I placed a floor fan facing the holes and temperatures, as reported by Temperature Monitor, plummeted.

So I had two choices. Run a variable low voltage DC power supply to the internal fan which had lost variable speed control – a royal pain – or simply slap a couple of large fans on the rear to ventilate the radiators and power supply.

As dismantling the iMac was getting old, I decided on the latter, at least for now. $40 and four cable ties later, I had two small utility fans, running very quietly off the mains, pumping large volumes of ambient temperature air through the ventilation holes with fairly dramatic results.

While I had the case open I also added cooling slots to the power supply plastic sleeve, after first detaching it from the power supply, thus:

Slots in power supply sleeve.

The Military Mac reports key temperatures.
Circled area denotes export of 80 RAW files from LR2 to JPGs on the Desktop.

Easily the most demanding task I have found, as cooling goes, is the export of RAW originals to JPGs out of Lightroom. That works the CPU, GPU and especially the power supply mightily. Look at the stepped rise of the green CPU line circled on the graph – that coincides with the export of 80 RAW files to the Desktop. The rise is easily within spec. That green line falls once the export job is completed. Note also that the other temperatures are largely unaffected, especially the power supply and GPU-related ones. That is indicative of the success of my approach.

By the way, the HDD fan, which I can still control with Fan Control, is set at 2200 rpm and cools a 1tB Samsung 7200 rpm 3.5″ SATA drive, which replaces the bottom-of-the-line Western Digital 250gB one these machines were shipped with. Hey, Apple has to keep up those profit margins. The Sammy retails for around $100 – a great bargain. As you can see, it runs very cool.

Why do I go to all this trouble?

Well, first, I do not like to be cheated, and Apple Inc. has cheated me by selling a faulty machine whose design faults they deny. Back in my old school, when a boy behaved like that, we stuck his head down the toilet, after first making sure no monks were in sight, and flushed. The designer of these deserves no less. I was quoted almost $1,000 to (maybe) repair a 30 month old computer with a short warranty, only to have it fail again? That makes no sense and is a dishonest and a dishonorable business practice. The replacement card cost me $260 delivered to my home in California.

Second, the 24″ S-IPS LCD screen in the iMac is quite superb for photo processing, and I would like to keep using it for a while longer. And it is matte.

Third, based on the hundreds of these refurbished graphics cards ApplePalace.com told me they are selling there must be many other users of these machines who might benefit from reading this. ApplePalace.com told me there is no such thing as a new card – they came clean on that and stated these are all refurbished by Apple, despite their web site stating parts are ‘new’. Hard to know what to believe here.

I had to use two external fans as I could not find one large enough to cover all the ventilation holes. If I cooled only the GPU-related holes the power supply would go into thermal runaway, quickly reaching 160F regardless of room temperature. So I went wild, blew another $18 and added a second fan.

How does it look? From the front the modifications are invisible and the fans barely audible. From the rear? Ugh!

Military Mac, ready for desert duty.

Will it last? I see no reason why not. Do I want to do this again? Please. I have no doubt that I will eventually simply rewire the internal fan to a variable power source I can control and get rid of those ridiculous excrescences, but right now I am in the land of function over form.

Now do you mind? I would like to finally get down to processing some photographs as I joyfully anticipate a world with a fail safe OS and hardware to match, regardless of who actually makes the latter. One things for sure – there will not be a fruit on the front.