PowerMac G5 PC Build

I come from academia where grants come and grants go and it's every professor's prerogative to burn through this year's NSF money before the next round of proposals are due. As such, the e-waste dumpster behind my building is always brimming with goodies from rack-mount servers to IBM extension cards. The other day I happened upon a pile of early 2000's Apple desktops, buried under which were these two treasures:

For all my griping about Apple, I love these machines from the first generation of brushed-aluminum-and-glass. They're so fantastically over-engineered it's more fun to take them apart than it is to actually do anything with them. Two heatsinks the size of von Clausevitz texts cool the twin PowerPC processors (which put out a whopping 1.6 GHz each) while nine gray plastic fans shuffle air around the 4-tiered case. While I'm keeping one of the G5's intact to use as a network box (pretty much all it's good for), I've decided to turn the other into an actual, useable PC. I'm going to chronicle my adventures with the PowerMac G5 in the rest of this post.

The first step is to completely gut the G5 and figure out where I stand in terms of parts. One of my goals is to maintain the exterior look of the case. The pictures below give a sense of the layout. The fans can all be re-used with a little rewiring, as can the front panel. Otherwise I think the only pieces I keep will be structural.

The ridiculous number of parts in the case.

The full tear down took hours with hundreds of tiny little torx screws that like to hide behind all of the weird structural features of the case.

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Okay, parts have been ordered! The breakdown:

$114.99 - ASRock Z87M Pro4 (uATX motherboard)

$239.99 - Intel Core i5 4670-K

$139.99 - G.SKILL Ripjaws X series 2X8GB (DDR3-1600, 9-9-9-24-2N)

$89.99  - SeaSonic M12II 620 Bronze 620W ATX12V

$69.99  - Seagate Barracuda 1TB 7200RPM 64MB cache SATA-III

Total (with tax and shipping): $696.93

The toughest decision was the motherboard. I ended up going with the uATX form factor to avoid having to cut into the top tray. I like the G5's HDD rack/fan setup so I wanted to preserve it as much as possible. My only concern is the uATX I/O panel which is shorter than the G5's so I'm not sure how I'm going to adjust for that. Everything should get here Monday and I can begin the fun part of this project (more fun than dropping $700 on computer parts at least...)

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The build

So my first step was to situate the motherboard. Everything else revolved around this. I chose to use the existing standoffs rather than a motherboard tray. To pop them out, I wrapped them in cloth (they are made of soft aluminum) and pried them off with pliers. The standoffs in the case come in two heights and I used the shorter ones for the motherboard to keep the I/O panel out of the way of the rear fans.

I aligned the motherboard to the PCI slots using an old networking card:

I secured the standoffs to the rear panel with JB weld. First I lay down some painter's tape to contain the epoxy. I scored the mounting surface with a screw driver to give the epoxy something to hold on to. Then I put the motherboard in place and wiggled it around a bit to get really get the epoxy around the standoffs. Finally I put some heavy books on the motherboard and let it cure for about 20 hours.

While the JB weld dried, I began work on the power supply. I wanted to use the original outlet so the first thing I did was slice open a standard AC power cord and solder it to the G5 outlet.

I like the plastic cover so I made sure to place the power supply far enough back in the case that it wouldn't get in the way of the strange depression in the cover (which I think is supposed to act as a venturi for the CPU fans). With the position measured I dremeled the shape of the PSU out of the top of the case. I made a space to reach the power switch as well as extra room in the back for the modular connections.

Probably the most time consuming part of this project was re-wiring all of the original G5 fans. I used three 'sets' of fans and will describe them in turn. For all three, I used these handy PWM splitter cables that I re-wired as needed:

The pins in the connectors can be removed by reaching into a slot in the front right above the pin and pushing down on a small metal tab. Remember to push the tab back up before reinserting the pin or it won't stay.

The first (and simplest) were the twin power supply fans. These aren't terribly important but I like the way they look so I left them in. The connections are very simple. One simply has a high line (red) and a ground (black), the other also has a tachometer wire (yellow). These run really loudly at 12V so rather than bother with a control (and since these don't really cool anything) I simply tied the high line to 5V (red wire in Molex connector) and left it at that.

The real fun began with the rear fan. Every fan in the G5 (except the PSU fans) is controlled individually leading to weird 4, 5, 6, and 8 pin connectors and all of the wires are black and unmarked. I used these pinouts and did not find any errors. To read them, hold the connector wires-down with the metal release tabs facing you:

To run the rear fan with a 4-pin connector, I soldered the control lines to the same pin and did away with one of the tachometer pins. I ended up with

Next up were the front CPU fans. I decided to use the one fan from this case (which was a single CPU machine) as well as the two fans from the dual CPU machine that I scavenged. I pulled the same trick with these fans, combining the control lines so that I could use the 4 pin connectors.

Since my motherboard was DOA and I had some time to kill while waiting for a replacement, I got a little creative with the fan placement. The first step was to pop the fans out of the the plastic framing, being careful not to tear the little silicon cones that hold them in.

Conveniently, the front CPU fans are exactly the depth of a 2X4 (~1.75") and so a couple of framing braces, drilled to mount the holes on the fan worked perfectly.

I used the dremel to make some aluminum bracing and held it all together with some #8x32x2" machine screws.

Lastly, I JB welded the framing braces to the rear panel and CPU cover. I think it adds just the right amount of pizzazz to the build.  

The hard drive bay fans were the last hurdles to getting the case nice and ventilated. I'm not sure why, but for whatever reason, the control of these fans seems to be only on or off. I was unable to change the speed by varying the control voltage so I resorted to simply tying the high line to 5V (like the PSU fans). Otherwise these were fairly straight forward. The reason for the 5-pin connector on the blower is also something of a mystery.

And the completed HDD bay with SATA cables, power and fans:

The only change I had to make to the exterior of the case was cutting the I/O panel out. As much as I would have like to rewire everything into the original ports, it made the prospect of ever switching motherboards pretty daunting. Instead, I simply cut the whole I/O panel out and will hopefully get around to crafting a nice faceplate out of sheet aluminum in the future. For now, it's just open to the world.

With all of the fans in place and the wiring all sorted out, I was ready to put the motherboard back in.

 

I installed the processor and memory and carefully lowered the motherboard in place.

The final step to a working machine was wiring the front panel to the motherboard. I used the following diagram for the front panel connector:

The only difficult part here is that the power button is connected to the firewire ground pin (top left of the diagram) and only to this ground. So three wires sufficed for the front panel: motherboard +PWR to pin 13 in the above diagram; motherboard +PLED to pin 14; and finally motherboard GND to firewire ground (not the shielded gnd pin) - pin 2 above.

And with that I was able to fire it right up. There are still a few issues that I need to deal with. The first is that my motherboard cannot seem to control the G5's fans. Apple being Apple, they are likely controlled by some very specifically shaped pulse known only to the engineers who developed the fans and who have now been permanently stationed on Eros (Ender's Game anyone?) For now the control is tied to 5V which seems to keep them at a reasonable speed. I would like to wire the front USB port and front headphone jack but I need to go out an buy connectors to fit the corresponding motherboard headers. Otherwise I'm rather pleased with the build. Kubuntu 13.04 installed with absolutely no drama and within a few hours this has become my new work machine. All in all, very pleased with this project.

Triumph Bonneville Carburetor Brace

Parts needed:
stainless steel tie-strap $2.00

Tools needed:
angle grinder
1/2" metal drill bit

Most of the airbox removal kits come with a brace to support the carburetors in the absence of the airbox's rubber boots. I made one myself for little cost out of a stainless steel tie-strap. First I cut the strap with the an angle grinder ($10.00 at harbor freight - gotta love those parking lot sales!).

The bar connecting the carburetors from the rear is just under 1/2" in diameter so I drilled a 1/2" hole close to the edge of the strap and used the angle grinder to open it up. I also reamed the the hole on the end of the strap to fit the bolt on the frame to which it will be mounted.

Allegra decided that the carb brace should be pink and so it would be.

Finally we mounted it to the frame.

Triumph Bonneville Mods for Airbox Removal

The Stock Airbox
Unfortunately the airbox can't be done away with completely because it holds the battery, acts as part of the rear fender and is a mounting point for various parts and systems. While the airbox removal kits offer a machined replacement to hold the battery and relocate mount points, we can do the same thing for much cheaper by chopping up the stock airbox. When cutting we have to carefully work around important features removing only as much as we need to fit the new air filters. I prefer not to destroy the stock parts on my bike so I ordered a spare airbox to tear up from a salvage parts dealer.

The battery box supplied by the kits provide a very minimalist replacement but as you're not using the space under the seat for anything else you may as well get creative with it. I decided to turn the air filter into a tool stash by tearing the pleats out with pliers. I clipped off the top and fitted some 1/4" vinyl tubing around the rim to keep it snug in its nook.

To make room for the new air filters, I had to cut from the front of the battery compartment, down and around the old-air-filter-turned-tool-kit. I used an angle grinder to cut most of the material off and then a hacksaw for the details. Both worked through the soft plastic like warm butter.

If you are planning to use the old air filter, make sure not to cut off the splines that hold it in place!

On the right side of the airbox are the rear brake reservoir and fuse box mounted on a metal bracket along with the carb heater relay press fit beneath the fuses. On the left side are two relay boxes and the starter solenoid. To make room for the new filters, the fuses, carb heater relay and starter solenoid all have to find new homes on the airbox. While deciding how best to go about doing this, my girlfriend hit upon the idea of using heavy duty velcro. This is great because it makes getting around the airbox for other maintenance much easier. Since the rubber mounts on my relays were toast, I decided to velcro those as well. The starter solenoid was relocated right next to the relays, while the fuses and carb heater relay moved to the front-facing side of the airbox.

A quick note about removing/installing the stock airbox: although I saw some posts online in which folks claimed to remove the stock airbox without removing the rear wheel, I was not able to do this. In the end I removed both springs, the rear fender, the left muffler (to access the axle bolt) and the rear tire. The extra space makes it much easier to fit the airbox and associated wires, hoses, etc. comfortably.

And that's all there is to it. Be sure to follow the manual closely when reassembling the rear of the bike. Don't forget to check the rear wheel alignment and tension the chain correctly before tightening the axle nut and make sure that everything is snug before calling it a day.

Triumph Bonneville Air Injection Removal

Secondary Air Injection System

Parts needed:
2 M12x1.25 bolts
2 crush washers

Total cost DIY:
$8.00
Cost at newbonneville/british-customs/bellacorse:
>$25.00

The SAIS is an emissions control system that pumps air into the exhaust to burn up any fumes that made it through combustion. Air travels through a hose from the airbox to a valve mounted on the frame above the engine and down two tubes that enter the cylinder next to the spark plugs. In order to aid combustion, a small amount of emulsified gas mixture is extracted from the left intake through a ribbed hose and also injected into the exhaust. Removing the SAIS is simply a matter of pulling it off the frame and plugging the holes where the hoses enter the cylinder.

Getting the SAIS out of the engine block is a little tricky if you don't want to mangle the metal tube because the hex is recessed and very close to the valve cover. Start by pulling the hose off of the reed valve.

Now turn the tubing around to expose the pinched hose clamp.

End-nipper pliers are good for opening these incredibly irritating hose clamps.

Now you can slowly ease the angle tubing leaving just the section that is screwed into the engine.

I slid an offset 13mm wrench down the tube to get at the hex. Be sure lay a shop towel down because you're probably going to smash the wrench into the cam cover when the threading breaks loose.

The hole left by the SAIS can be filled with a M12x1.25 bolt. This is a pretty uncommon size (at least in the US) but luckily it is the same spec as the drain plug for many Japanese car models. You can find one for a few bucks at your local auto parts store. Don't forget to buy M12 crush washers as well!

If the drain plug is too long or has a stub (like the one I got) you can cut it down to size with an angle grinder.

The crush washer is extremely important as this bolt has to seal the against the exhaust pressure. Aluminium and copper are both good choices. Remember that the space around the SAIS hole is very limited so the washers should be small. The two washers pictured below were too wide and I had to go out and buy new ones. Save yourself the extra trip!

Simply bolt the drain plugs into the engine and you're good to go!

Triumph Bonneville DIY Air injection and Airbox Removal

So I know that airbox removal has been pretty much beaten to death (at least by the Triumph community) but as I managed to save quite a bit of money doing this myself (not with a kit) I figured I'd document it. This modification replaces the stock airbox with individual air filters clamped onto each carburetor intake. The airbox snorkel and internal baffle restrict the flow of air into the carburetors; by removing the maze of plastic, we free the carburetors to draw in more air resulting in a modest performance increase. I'm going to skim through the steps that are explained elsewhere and focus on the parts that involve a little creativity and ingenuity.

For starters, airbox elimination consists of a few distinct parts. In no particular order (click the link for a detailed walkthrough):

the stock airbox has to be chopped to make room for the new air filters;
the carburetors have to be re-tuned to adjust for the increased airflow;
the secondary air injection system should be removed;
the carbs have to be braced against the frame;
the new filters need to be installed;
the crankcase breather hose must be re-routed and fitted with its own filter.

Finally, the carburetors need to be balanced and and adjusted until everything is running up to spec.

Instead of compiling one monolithic article, I've broken these down into a few self contained posts to keep things relevant.

Parts
Airbox mods:
2 K&N RC-1920 air filters (54mm I.D.)
1 stock airbox
heavy-duty velcro

AI removal:

2 M12x1.25 drain plugs
2 M12 crush washers

crankcase breather:
1 K&N 62-1015 crankcase breather filter

2 1/2" hose clamps

15/32" PCV hose

For carb tuning:
main jets, pilot jets, needle shims