Sonnet Encore/ST G4 Duet Installation

The original dual-processor system, plopped open, as shipped from Apple:

1. A separate cooling fan mounted on the back panel; draws air through the heat sink (2) and pushes it out the back of the machine.

2. The aluminum heat sink clamped to the top of the dual processor daughtercard. The little warning sticker must be the International Symbol for Sizzle: made me wonder if college students have used these like a hot plate. "Want some ramen? Hold on, let me boot the G4..."

You can also see my two PCI cards (an Nvidia GeForce TwinView in the AGP slot, and an ATI Radeon in a PCI slot). At the time, getting a separate video card for my second monitor was cheaper than trying to adapt Apple's ADC connector to VGA. I'm not a gamer or video editor, so I'm not deeply concerned with maximizing graphics performance. Also: no AirPort card! Since I own nothing else with wireless capabilities, it seemed pointless.

The orangy surface? That's my coffee table, which is just two side tables pushed together. Don't laugh: it had better light (and far less clutter) than my desk!

The rear fan attaches to the back of the G4 using two Philips screws; in this image I've removed the fan, unplugged it from its power supply on the motherboard, and set it to one side. It wasn't very grungy (surprising! I have three cats and a lot of dust), but I'll clean it out with some compressed air and spray some silicone lubricant into it before I reinstall it.

Here's the only tricky part of the process: two clamps hold the original aluminum heat sink to the processor daughtercard; the clamps are easy to identify, and sit in extra-wide grooves between two fins on the heat sink. In this image, you can clearly see:

1. Clamps holding heat sink to daughtercard

2. Edges of the daughtercard

To remove the heat sink, I'm following the instructions from the Sonnet installation materials almost precisely: press the top of the clamp using the point of some needlenose pliers while giving a little outward twist to the clamp using a standard screwdriver. The pliers just keep the clamp from flipping up when it's released—you could just as easily use a pen or whatever's handy. The clamps come off with a satisfying (or heart-stopping, depending on your point of view) thwack!

The shiny metal rod next to the motherboard battery is the leg of my camera's mini tripod. No, it's not actually touching the motherboard!

Once the original heat sink has been removed, Mac aficionados might find the following images the most disturbing. My, those G4 processors certainly look extra crispy! And look at those... can those be scorch marks on the bottom of the heat sink?! Do the G4s really put out enough heat to burn aluminum?

Well, no. The melting point of aluminum is about 660°C; if the G4s got that hot, anyone using a G4 PowerBook would probably be dead. Instead, you're seeing the remains of a thermal conductive paste Apple applies to the processors to ensure they efficiently transfer heat to the heat sink. A good seal helps even things out.

This highlights another interesting point of a processor upgrade: if for any reason you want to re-install your original processors, you probably can't just put everything back together again. It'd be a good idea to clean off as much of the old crud as you can, and use new paste. I can't offer concrete advice, but thermal paste (or thermal grease) is commonly available in electronics stores and is usually a mix of zinc oxide and silicone. Different products have different conductivity ratings: higher is better, but I don't know what a realistic minimum might be. A little goes a long way; apply as little as possible while covering the contacting surfaces. You don't want any extra slopping out onto your daughtercard.

You can also see (1) four Philips screws holding the daughtercard in place. And no, I can't make out what's scribbled on (what I presume to be) one of the L3 cache chips. (2) A message from space aliens? A secret code saying "Mac OS X won't run for Geoff" from Steve Jobs himself? It was that way when I opened it up—honest!

It turns out to be difficult to photograph much of the Sonnet Encore/ST Duet installation process: it's surprisingly simple. You have to attach a small add-on board (1) which connects to the motherboard's main power supply (making this part separate presumably reduces the amount of redesigning Sonnet has to do to get its processor upgrades into different Apple systems). Attaching the power supply board took me all of two seconds and was over before I even considered photographing it.

Another interesting part is the actual socket on the bottom of the processor daughtercard which attaches directly to the systems's motherboard. You remove a protective cover from the connector on the Sonnet card, use it to cover the same connector on your pre-existing processor card. These are not the same as the ZIF sockets used on earlier G3 Macs, but there doesn't seem to be a common name for them.

Placing the processor card is simple: the G4 motherboard has four threaded posts which serve as guides: just gently push down until the two boards snap together, then lightly tighten the Philips screws - one of which is re-used from the original daughtercard. The Sonnet heat sink is a (very hip!) purple anodized aluminum, although it also contains a copper plate in direct contact with the G4 processors. The heat sink is pre-attached to the Sonnet upgrade so there's no fussing with it. The heat sink comes with its own fan (3, also pre-attached)—although I still have to replace the fan I removed when we opened up the machine. If you're counting, yes, the computer's going to have one more internal fan than it did when we started.

The second image shows the Sonnet Duet from the top: you can clearly see the two "levels" of the heat sink, and that the built-in fan pulls air into the taller (darker purple) section of the heat sink.

Finally, here's the completed installation, with Apple's original fan re-installed to push air out the back of the machine - it's the black plastic bit above the purple area of the processor upgrade. I did take the liberty earlier (when I first removed the fan) of blowing out the fan's innards with some compressed air and spraying in a bit of silicone spray lubricant, since the fan had occasionally made a fair bit of noise when it got "excited" usually on hot summer days when I had to get TidBITS out the door. In fact, since I probably heat a good portion of my home office with my G4 during the winter months, I want its fans to be operating at peak efficiency!