Hey guys! If you know me, you'll probably be familiarized with the fact that...

I. Am. Obsessed. With. The. iMac. G3.

Yeah, it's my second favorite computer behind the eMac, I have four G3's in the very room where I'm writing this post.

Many people share this sentiment, as the iMac G3 was—by many—considered revolutionary.

For a very long time, computer and monitor were two different things. The computer would process data, and the monitor would display the results. The two were completely independent electronic devices that could work independently of each other.

In the image above, please note how silly the monitor looks. This, however, is an illusion. The monitor isn't being silly, the computer is! Behind those layers of motherboards and metals, is the silly face being displayed in the monitor (in the form of mathematical equations and vectors).

The computer, though, needs to send the silly face to the monitor in order to show us, the user, that it is being silly. With that said, the monitor is not being silly, it's just displaying the computer's silliness.

So, a computer could operate without a monitor, and a monitor could be used with devices other than a computer.

Out of these two, only the computer needed a cooling system. In most cases, cooling would involve a tiny fan: The fan would suck in some cool air into the machine, and spit it out along with the internal components' heat.

Wait, but why did monitors not need cooling? Well, I'm glad you asked! Here are a few key factors:

Efficient Heat Dissipation

CRT monitors generate heat, but the way they are designed allows for effective passive heat dissipation. For example, the uhm, enormous glass tube, or the metal components inside, like the shadow mask and the electron gun assembly, radiate and dissipate heat naturally. The large surface area of the glass screen itself also helps in dispersing the heat over a wider surface area.

Lower Power Density

It is true that CRTs consume a large amount of power. However, the power density (amount of heat generated per unit of volume) is relatively low compared to modern electronics like LCDs, GPUs, or CPUs. This means that the heat generated inside a CRT is spread out over a larger volume, reducing the need for active cooling like fans. This is not so much a property of the CRT itself, but its bulky size. Still an advantage, nonetheless!

Convection Cooling

If you've ever been around a CRT, you'd know that their design of typically includes tons of ventilation holes or slots. These allow air to naturally circulate through the monitor (and also burnt dust particles to fly out, giving you that nostalgic smell of burnt dust we all love). This enables the monitor to have passive convection cooling. As hot air rises and escapes from the top of the unit thanks to weird laws of physics, cooler air is drawn in from the bottom or sides, maintaining a stable temperature without the need for fans.

Lower Operating Temperatures

The components in a CRT monitor, like the electron gun and deflection coils, operate at temperatures that don't require intensive cooling. The materials used are also more tolerant to the heat levels produced during normal operation.

In a nutshell, CRTs are BIG, and physics are weird!

This traditional setup changed with the introduction of the iMac G3, which combined the computer and monitor into a single unit.

With the iMac G3's all-in-one model, where both the monitor and the computer were part of the same system, nothing really changed. All-in-one had been an established model for quite a long time by then, but it wasn't that much widespread.

The iMac G3 was the first all-in-one computer to provide such a revolutionary and unique design. Heck, it looked incredibly weird, but it looked great! Its engineering, though? Eh, it wasn't the best.

As you already know, I've been incredibly enthusiastic about the iMac G3 for a very long time now. Not just because of how cool it looks, but also because of how poorly designed it is in many ways. The main one being how stupidly stupid cooling is.

To the end user, cooling issues are as apparent as the fact that the computer tends to overheat when you aren't using the dock.

But oh, they go way beyond.

This is how cooling works in the iMac G3. The computer generates heat, sucks air from below the computer (thus why you need to use the dock to avoid overheating) and spits it out to the monitor.

Let's go back to the example from earlier. Imagine your classic computer setup with a separate monitor and computer, but there's a pipe attached between the two that funnels the computer's hot air right inside the monitor.

Now, before wondering if the computer's violent tendencies come from something deep within, we need to wonder if this will be an issue for the monitor. The answer is, yes! This unified design created a scenario where the CRT was being subjected to additional heat it wasn't originally designed to handle.

This not only increases the operating temperature of the monitor but also places additional stress on the cooling system. Over time, this could lead to issues like overheating, reduced lifespan of components, among other things.

How is the G3's cooling different from this analogy? Oh, well, IT'S NOT!

The iMac G3’s cooling system effectively turned the CRT monitor into a passive participant in the computer’s thermal management, forcing it to endure heat levels it wasn’t initially designed for. This setup not only increased the overall operating temperature of the monitor but also put the delicate internal components under stress, leading to several potential issues.

As a matter of fact, there is only one thermometer in the whole machine, inside the computer! The monitor's temperature is never taken into consideration. That means, if the monitor is begging for a lower temperature, even if it's literally on the brink of meltdown, the computer won't be able to know, and thus, it won't act accordingly.

The iMac's design assumes that convection cooling could take care of the added heat, when this couldn't be farther from the truth.

When convection cooling doesn't cut it

As seen earlier, convection cooling is a method that relies on the natural movement of air to dissipate heat, using ventilation slots and the design of the chassis to encourage airflow. In theory, this sounds great—no moving parts, no extra noise, just the gentle rise of warm air and the influx of cooler air to keep things cool.

However, when it comes to the iMac G3, its dependency on this approach quickly reveals its limitations.

The iMac G3's sleek, compact design is undoubtedly one of its most attractive features, but it also means there’s less room for air to circulate. The computer's internal components and the CRT monitor are packed into a tight space, with minimal room for convection to work effectively. As the internal temperature rises, the narrow vents and confined space struggle to maintain adequate airflow, making the convection cooling system less effective.

1. Heat Accumulation With the CRT monitor absorbing the excess heat from the computer, the temperature inside the iMac G3 can and will steadily climb, particularly during extended use. Convection cooling is inherently slow and passive, which means it often can't keep up with the heat being generated. The result? Heat builds up faster than it can be dissipated, leading to gradually increasing temperatures that the system simply isn’t designed to handle.

2. Environmental Factors Convection cooling is highly dependent on the environment in which the iMac G3 is placed. If the ambient room temperature is high, or if the computer is placed in a confined space with limited airflow (like against a wall or inside a desk cubby), convection cooling simply won't apply. If the air that's surrounding the computer is as warm, or even close to the warmth of the air inside the computer itself, then convection cooling won't even work. The design didn’t account for these real-world scenarios, leaving the iMac G3 vulnerable to overheating in less-than-ideal conditions. This is an even worse issue in places like Spain, where the air tends to be humid and warm.

3. Lack of Active Cooling Solutions Most traditional computers of that era used a combination of convection and active cooling—fans or even heat sinks—to manage temperatures effectively. By relying solely on convection, the iMac G3 lacked a critical layer of protection against overheating. When convection cooling couldn’t keep up, there was no backup system to step in and help regulate the temperature, incrementing the risks to both the computer and the CRT monitor.

And, you know what makes this so frustrating? This could have been easily preventable without making many changes to the design! A thermometer near the CRT would have been enough to let the computer know that it needs to work harder. Some extra noise isn't an issue when a CRT is on the line.

Here are some of the issues that heat stress can cause to the iMac^(source):

• Flyback transformer failure (common)
• Brittle internal plastics (common)
• PAV (Power, Analogue, Video) board failure (common)
• GPU failure (common)
• Clock battery leakage/corrosion (common)
• Rotting speakers (common)
• Cracked/dry solder joints

There has to be a solution.

You could drill holes into the computer, you could install more fans, somehow, or you could...

This sucks.

Yeah, most solutions really suck, as they involve modding, but do they have to?

Listen, I've had an idea, but I need your help. Yes, your help! Listen:

G3 iMacs are no longer manufactured. We can no longer use them because they won't get fixed, but we also can't really not use them, as lack of use will wear them out.

All computers deserve preservation, and a second life. Simply finding a cooling solution that doesn't involve opening the case could help tons. So, listen to my idea. Instead of having the computer struggle to keep itself cool, why don't we lend it a hand?

Imagine a small, open-source 3D-printable gadget that can hold two standard computer fans, that snugly fits into the top vent of the mac. The two standard fans could be hooked up to a USB cord, connected to the computer itself.

No modding, no opening the case, no nothing. Just an amazingly simple tool for cooling and proper preservation.

This is a passion project I've been silently working on. I've been calling it "CoolAssist", not the definitive name though. ;)

How You Can Help

I believe preserving the iMac G3 and keeping these iconic machines running is a cause worth rallying behind. But, I can’t do it alone—I need your help to bring this idea to life.

You can get involved in the following ways:

• Spread the Word: Share this post with anyone you think might be interested in retro computing, the iMac G3, or tech preservation. The more people who know about this project, the better our chances of success.
• Support the Project: Unfortunately, bringing this idea to life isn’t cheap. As a matter of fact, I've already spent 70 euros just doing the preparations! If you believe in this project, consider making a donation to help kickstart it. Your contributions will go directly towards the development and production of the cooling solution. Every little bit helps. If you're interested, please contact me!
• 3D Modelling Enthusiasts Needed: If you’re a 3D modelling enthusiast or know someone who is, I would love to collaborate. Your skills could be crucial in designing this cooling solution. Contact me!

And... A gift

Enjoy!

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