My Cheapest iMac Yet

Just bought an iMac for our school. It’s a second hand but pristine G4 iMac 15″ 700MHz machine, just like the one I bought last February. It still even had the wrapping on the vertical tube supporting the screen and the little pair of ball speakers.

The shop assistant told me that it would run for about 30 minutes before shutting down. Curious, I asked if I could plug it in. He left me to it and I switched it on. Immediately, I saw the problem. The fan was rotating so slowly the blades were visible.

I’ll buy it! I said and walked home with a ¥3,980 (A shade over 20 quid) iMac.

Not wanting to open my currently working iMac again, I decided to check on line for the required fan replacement. A quick check of http://www5.plala.or.jp/kdreview/imac_g4_17.html showed the fan to be a 92mm x 25mm Superred part.  I remembered it from the one I opened last year, so even though it’s not the same machine, I bought it with confidence, along with an old 512mb PC133 stick of RAM.

I opened her up, replaced the fan and RAM,put her back together (a thirty minute job) and an hour after switching on later, the machine is still running.

Nice. I’ll have something to run iTunes on in our café section, now.

Powerlogix 1.5GHz 7447A CPU Upgrade for Cube benchmarked

I finally got around to benchmarking my G4 Cube with its new Powerlogix 1.5GHz 7447A processor. 

Here are the X Bench results, for what they’re worth. They are quite variable, but this is the average from about four or five runs.

X Bench Benchmark Results (Taller is better)

The results show Gains across the board, with, as expected the major gains shown in CPU and Thread performance.

Interestingly, since the graphics card is the basic ATI 16MB Rage Pro, the graphics are majorly CPU dependant and those too showed major gains.

In fact, as expected only memory and HDD showed no real gains.

These facts bare out well with the actual usage as shown here:

Boot Up time (Shorter is better)

The above chart shows the waiting time until the specified event occurs.

Up until the Apple logo appears, the two machines behave identically. From that point on, the 1.5GHz CPU pulls ahead significantly. If one starts timing from when the what Apple appears, the 1.5GHz Cube is approximately twice as quick.

Login Time (Shorter is better)

My login is packed with various applications and I think is a reasonably good test of overall system performance with a bias towards uncached disk access. The above chart appears to bare this out with an approximate 40% speed boost.

Application Launch Times (Shorter is better) 

 

Here you can see with application launch times that most launch speed is doubled. And, where there is a low dependancy on the hard disk (i.e. relaunching) then the speed advantage is treble in the case of Microsoft Word and Photoshop CS3.

One pontential issue is the temperature.

With the old 450MHz CPU, the Cube would show the internal HDD’S SMART temperature reading Idling around 37C in a temperature controlled 24C room.

Due to complete lack of any power saving facilities, even at full CPU load with moderate disk access, the active temperatures rarely rose above 39C.

Now, with the 7447A 1.5GHz CPU and NAP activated, it idles at 38C but quickly moves up to 42C or 43 when using iWork.

I’m concerned about the extra heat, so I may replace the currently silent fan with a more robust 12V 80mm effort!

So, overall this upgrade, an incremental investment of $250 half paid for by my employer has brought my computer forward one or two generations. It’s moved from a usable but ultimately frustrating computer to one which can be used heavily for numerous office and browser tasks without getting bogged down.

Installing Powerlogix 1.5GHz 7447A CPU Upgrade for Power Mac G4 Cube

I bit the bullet yesterday and upgraded my Power Mac G4 Cube from its original 450MHz processor to an overpriced 7447A Power CPU in the form of a Powerlogix CPU Upgrade.

First up, I had intended to purchase a chip with a VRM bypass but when it arrived, I found that I’d mis-ordered and got a vanilla version without.

I checked the website more closely and yes, indeed the version I had ordered did not have the VRM.

I would have sent it back, but unfortunately, I ordered it from OWC in the US, so that’s not going to happen.

Here are some extra hints if you want to replace your CPU with a Powerlogix one. These are not complete instructions in and of themselves.

Before you start, watch the video and print and read through the instructions. They are clear on most counts but I found a few areas lacking.

Here I’ll list a few of the difficulties I faced while also listing the outline of the instructions

Firmware Update
  (in a nutshell) 

• Insert the CD with the Cube powered up. Then shutdown the Cube
• Now hold down the programmers button and keep it held until the power light flashes rapidly then press and hold C until the firmware screen appears.
• At the menu
• Press 4
• Wait for the process to complete.
• Press 5 if you use OS 9.

 Now this bit was a bit worrying, nothing was mentioned what to do after the above steps. 

• Just press the option to shut down the Cube
• Proceed with the disassembly.

Graphics Card and VRM

• Ground yourself.
• Remove all cabling.
• Pop the chasis.
• Remove the top plate.
• Be careful with the power connector between the top and the chassis. It’s quite short.

fig 1

You do NOT need to disassemble the whole chassis in order to remove the CPU.

• Just turn the cube on its side (GFX card up) and remove the two posts. Remember which way they go, they look very similar but won’t fit if you get them in the wrong place or the wrong way around!

fig 2

• On this side of the motherboard, you only need to remove three screws. 

 
fig 3

Removing the Video Card

The first real challenge you will encounter is removing  the video card. The cube is tight and the card is connected to a riser from the motherboard rather than directly to the motherboard itself.

• MAKE SURE YOU’VE REMOVED THE TWO SCREWS that hold the GFX card to the frame. They are located on the base of the Cube and flank the VGA and ADC connectors.
• Remove the Video Card and Riser card together. It’s not possible to remove the card by itself.

The main difficulty is that the ports are stuck through holes in the base, which prevents you from lifting the GFX card and riser vertically, you have to lift just the point shown below.

Don’t worry, the connector is quite tough and the angle won’t break any pins or edge connectors if you are careful.

Try not to lift the GFX card out too far at first and be careful of the wires connecting the GFX card to the motherboard.

If you are having difficulties with the GFX card assembly, you might want to remove the VRM first, which is considerably easier to get out.

fig 4

The black connector shown below comes off easily. Just push down on the protruding part of the clip like a clothes peg and pull the clip out.

fig 5

Try as I might, I was unable to remove the brown connector shown in the picture above.

Instead, I just pulled the GFX card from the riser and hung the riser over the side of the chassis, out of the way, making sure the light grey wire (shown towards the right of the above photo) was OK.

Removing the VRM

Once the GFX card is out of the way, it’s relatively easy to remove the VRM module (That’s the other riser on the right), opposite the RAM slots.

Since I had some difficulties removing the GFX card, I removed the VRM first, to give me more space, but the principle is the same.

There is a little grey catch toward the back of the unit, next to the VRM module.

• Use a screwdriver to release it by sliding the catch to the left (if oriented as shown below). Note that there is very little feedback from the clip. Just push it back gently while pulling the VRM up and out, vertically.

fig 6

Extracting the motherboard

In order to extract the motherboard, you need to ensure you have done all of the following:

• Removed the GFX card.
• Removed the VRM.
• Unscrewed the two motherboard screws along the front edge of the board as shown in fig 3.
• Removed the “unique screw” from near the VRM. (fig 7)
• Removed the “long screw” from near the memory slots. (fig 7)

fig 7

• Unscrew the three, spring-loaded screws from around the large grey chip in the middle of the motherboard and pull them out vertically. Mine were quite stiff and required wiggling to get them out.

fig 8

Before you can extract the motherboard, it has to be released from the big central heatsink beneath it, which due to heat and time will have fused itself to the CPU’s heatspreader because of the thermal sheet between them.

I found the method used to separate the two from each other very difficult. Perhaps because my screwdriver was too big. I couldn’t get it between them to start prying them apart.

• I started from the corner by inserting my screwdriver and twisting gently. The heatsink came away easily enough.

fig 9

Once you’ve lifted the motherboard away slightly from the big heatsink, pull it towards you, away from the bottom of the case, with all the ports on it and parallel to the central heatsink.

Remember, there are two posts guiding the rear of the motherboard. If you lift the motherboard rather than pull it towards you, you risk the motherboard’s supporting corners being snapped.

Note that the ports on the bottom of the Cube are pushed through holes in the base. These holes are sealed with a kind of metallic springy foam, probably for shielding.

You will have to pull the motherboard away from the base with a little bit of force, since the springy foam may have got quite hard with time.

Replacing the CPU and heatsink

• Remove the old CPU carefully.
• Replace with new CPU.

This next part is optional, but I hightly recommend it

• Scrape off the old thermal compound from the back of the big black central heatsink.
• Apply a thinly spread layer of heatsink compound to the new CPU’s heatspreader.

fig 10

Install the base fan – DO NOT FORGET. THIS IS NOT OPTIONAL. Running the upgraded Cube without a fan will destroy it!

Now follow the instructions and put everything back together.

Once you hear the Apple Bong, CHECK THAT THE BASE FAN IS ROTATING AND BLOWING AIR UPWARDS. IF THE FAN FAILS, SO WILL YOUR CUBE.

128Gb+ Large HDD (LBA48) support on the G4 Cube with Leopard, for free.

It’s possible to access the entire space of any large hard disk without drivers, that means without the need for the $25 Speed Tools ATA Hi-Capacity Support Driver. This also means that Leopard will work, too.

With the magic of the Open Firmware, as with the Open Firmware fake CPU speed hack, it’s possible to hack the Open Firmware to enable large disk support, otherwise known as LBA48.

I have only tested this with Leopard and Tiger, so I can’t vouch for earlier OS-X builds. however, note that this DOES NOT WORK FOR OS9. For OS9, you will still need the speedtools driver available here:

• http://www.speedtools.com/ATA6.shtml

This time, however, we need to write this to the non-volatile RAM so that the changes aren’t lost on reboot.

• Reboot or Power up your Cube
• Hold down Command + Option + O + F simultaneously as soon as the reboot starts.

You should now be at the Open Firmware prompt. Note that this is NOT the BASH prompt, so don’t try anything here.

• Type in the following, exactly. Please note that the Underscore “_” is used to indicate a space.

nvedit
dev_hd
dev_..
"_"_"_lba-48"_property
device-end

• Press Ctrl+C to exit from nvedit.

nvstore
setenv_use-nvramrc?_true
reset-all

That’s it. Now boot up and go to “About My Mac” to confirm the disk size.

If your disk was already formatted, it will have its original 128Gb partition and a region of inaccessible space at the end. It’s probably easiest to reformat the disk with a new partition scheme, unless you have some terminal disk utility or related tricks up your sleeve.

• This hack will last until you reset the NV RAM (P RAM).
• Similarly, if you hose your open firmware settings, use this fact to your advantage, perform a PRAM reset and start again.

If you do repartition the disk, it’s probably wise not to cross the 128Gb boundary with a partition, in case you ever have to reset the NV RAM, in which case you’ll only be able to access the first 128Gb of the the hard-disk. By splitting the disk at 128Gb, you’ll ensure that only whole partitions are visible and any partition after the 128Gb will be entirely invisible.

In my case, I made a front partition of 128Gb, and the remaining 30 something Gigs into an extra partition for temprorary files.

Thanks to the Cube Kaizou (Cube Mods) page on Studio Milehigh (!!!) homepage. Apparently his own Cube died at the end of April last year but he has left his legacy of Cube update experience online.

• http://homepage.mac.com/milehigh/golive/index.html

Adding a thermometer to the G4 Cube.

After replacing the original 20GB drive with a nice new one, I got a little concerned about the temperature. I’ve installed a 1200 rpm, practically silent (19dB) fan in the base and wonder if it’s enough to offset the heat generated by the 7200rpm Hard Disk. 

So, for the the third and final installment on modestly modding my Power Mac G4 Cube, I’ll show how and where I added a thermometer to measure the drive temperature. This should take about five minutes.

Get yourself a nice digital thermometer with a surface contact probe, like this:

 

The temperature probe should be small enough to fit through one of the holes in the bottom of the Cube’s casing:

Opening the case:

      First make sure you have the thermometer, some aluminium tape and enough room to work on,  i.e. a flat, clear surface within easy reaching distance.

• Unplug the Cube and invert it. Take care not to scratch the machine’s plastic case. I inverted mine onto a pillow.
• Push the rectangular, inset bar located on the upturned base in firmly, until you hear it click. Now release it. The handle should pop out.
• Use the handle to lift the chassis out of the upturned case. If this is the first time it has been removed, it might take a little teasing to get things moving.
• Lift the chassis out vertically, taking care not to scratch the insides of the case with the metal corners of the chassis. The chassis has no sharp corners so this is not a serious issue. Still, it would be a shame to scratch it.
• Now place the chassis down on a flat, clear surface. Take care not to damage the sensor on the top of the unit (probably facing downwards since it’s the side opposite the handle).
• Push the handle in all the way and let go. It should stay in place.

Connecting the Thermometer

• locate the side of the Cube where both the RAM and the HDD are visible.
• Push the probe up through a hole in the bottom of the case. Somewhere near the BIOS battery is a good area.
• Pull in as much wire as required and bind the wire tightly with a wire tie to one of the internal posts. There is a space above the Airport sensor on the the side, perfect for this purpose.
• Tape the sensor to the side of the drive firmly with aluminium tape.

Now reassemble the computer.

I found that when actively using the Cube, the drive would reach about 40 degrees when active. A lot cooler than the 55 degrees it used to reach before installing the fan.

 

Installing a Large 128Gb+ Hard Disk in the Mac G4 Cube

I’ve been running my G4 cube with a large hard drive since just after I bought it in May, 2005. I thought it was time to show you the quickest way to replace the drive in 10 minutes, without any major disassembly.

The Cube is a product of its day and I’ve had mixed results with high capacity drives in my Cube, including drives that “should work”.

Firstly, bear in mind that if your drive is larger than 128Go (A Go “Giga Octet” is the new way of saying GB when you mean 1024x1024x1024 bytes rather than 1,000,000,000 bytes that the drive manufacturers use to inflate their drive sizes 128Go is about 132GB) , you’ll need to purchase the

Intech ATA Hi Capacity Driver for Mac OS X

Or else your computer will only recognise the first 128Go, regardless of the drive size. I’ll discuss this in a later post.

Update: You can use an Open Firmware hack to achieve the same thing. Read here.

You’ll need a set of Torx drivers for the star shaped “security” screws. Sizes T8, T10 and T12 should do the trick. You will also need a medium sized pair of pliers for some minor and painless case modifications.

Opening the case:

       First make sure you have the fan, the torx drivers and enough room to work on,  i.e. a flat, clear surface within easy reaching distance.

• Unplug the Cube and invert it. Take care not to scratch the machine’s plastic case. I inverted mine onto a pillow.
• Push the rectangular, inset bar located on the upturned base in firmly, until you hear it click. Now release it. The handle should pop out.
• Use the handle to lift the chassis out of the upturned case. If this is the first time it has been removed, it might take a little teasing to get things moving.
• Lift the chassis out vertically, taking care not to scratch the insides of the case with the metal corners of the chassis. The chassis has no sharp corners so this is not a serious issue. Still, it would be a shame to scratch it.
• Now place the chassis down on a flat, clear surface. Take care not to damage the sensor on the top of the unit (probably facing downwards since it’s the side opposite the handle).
• Push the handle in all the way and let go. It should stay in place.
• Turn the case, so that the sensor is now facing upwards.

Removing the drive heatsink:

• Locate and remove the three Torx bolts which hold the drive hatsink in place as shown above. Note that the bolts are captive, and as such do not actually come out. This is a great Apple design point, since it stops the bolts from falling into the machine!
• Now lift out the heat sink itself.

Removing the drive:

• Locate the airport card flap on the side of the unit.

• Open the Airport door. It will swing out. Don’t worry, it’s well hinged and won’t fall off!

• Remove the drive power connector – Mine was stuck firmly and required pliers to release it!

• Now remove the ATA connector.

• The drive should now slide out from the opposite side of the chassis.

• Remove the guide rail from the side of the drive.

Replacing the drive:

• Don’t forget the plastic drive guide rail
• Slide the drive back in. 
• (Optional) You may want to coat both sides of the three steel posts which hold the drive with a drop or two of heatsink compound, since new drives run much hotter than the old 20GB drive that was in there and every bit of cooling will help.

• Replace the bolts which hold the heatsink.
• Replace the data and power connectors.
• Close the Airport card door. Make sure the airport antenna cable  is taped  firmly to the door if you don’t have an Airport card installed.
• Put chassis back in case, connect and power up. 

 

Installing a fan in the G4 Cube

Many Mac purists out there will shake their heads and disagree vehemently, but with spares for the remaing cubes starting to thin out, a fan is essential in keeping your cube healthy, and I heartily recommend one to anyone who uses their cube for more than a couple of hours a day.

The Mac G4 Cube was designed to hold a fan. Even though in it’s original incarnations (450MHz and 500MHz varieties), there was no fan installed, the case itself has a place to hold an 80mm fan of about 20mm thickness and with a little effort, one can crowbar a 25mm thick fan in for more effective cooling.

Be careful when selecting the fan. The one I bought was a silent, solidly built one which had supporting tubes around the corner mounting holes. It seemed like a good idea at the time. However, these turn out to make installing the fan without disassembling the whole case impossible. A lighter fan without supports on the corners would have been much easier to install. In any case, I used a hacksaw and cut two adjacent supports along the edge which eventually ended up towards the back of the Cube.

I bought myself a nice, quiet 80mm x 25mm 1900 RPM fan. They tend to be about 3~6db quieter than 20mm fans which push the same amount of air. It came with 3 wires, red, black and yellow

Replacing the fan is actually a little more time consuming than replacing the hard disk, but not really much more difficult.

You’ll need a set of Torx drivers for the star shaped “security” screws. Sizes T8, T10 and T12 should do the trick. You will also need a medium sized pair of pliers for some minor and painless case modifications.

Opening the case:

      First make sure you have the fan, the torx drivers and enough room to work on,  i.e. a flat, clear surface within easy reaching distance.

• Unplug the Cube and invert it. Take care not to scratch the machine’s plastic case. I inverted mine onto a pillow.
• Push the rectangular, inset bar located on the upturned base in firmly, until you hear it click. Now release it. The handle should pop out.
• Use the handle to lift the chassis out of the upturned case. If this is the first time it has been removed, it might take a little teasing to get things moving.
• Lift the chassis out vertically, taking care not to scratch the insides of the case with the metal corners of the chassis. The chassis has no sharp corners so this is not a serious issue. Still, it would be a shame to scratch it.
• Now place the chassis down on a flat, clear surface. Take care not to damage the sensor on the top of the unit (probably facing downwards since it’s the side opposite the handle).
• Push the handle in all the way and let go. It should stay in place.
• Turn the case, so that the sensor is now facing upwards.

Opening the chassis

In order to put a new fan in without a complete disassembly, it is necessary to remove the optical drive.

• Remove the top plate by taking out the four corner bolts and two bolts on either side.

• Lift off the top, slowly and remove the small cable which connects the power sensor to the chassis.
• Place the top panel somewhere level, avoid touching the sensor.
• Now slide the plate with the orange spot on it slowly up and out, revealing the optical drive.

You should now see the drive exposed as the picture below shows. 

• On either side of the drive, there are some screws, holding it in place. Remove these screws on the sides of the optical drive to release it.
• Slide the drive upwards and remove the power and ATA cables from the connectors.

• The drive can now be removed, revealing the gap at the bottom of the case for the 80mm fan.

Installing the Fan

• In order to slide the 25mm fan into the case without disassembling the whole thing, we need to bend the fan supports out to the sides until they allow the fan to slide in.

• Note that there are two further holders at the rear of the case which may prevent your fan from fitting.
• If your fan has corner posts around the holding bolts, remove two of them to allow the fan to slide into place. 

• Bend the supports back around the fan to ensure a snug fit, as shown in this example picture below.

• After playing around with the supports for a bit, I taped around the fan with duck tape after breaking the two back posts. This also helps reduce vibration noise, but this is not necessary.

Connecting the fan to the power

It’s now time to connect the fan to the power supply. We will use the optical drive’s power supply which we have at hand since we removed the optical drive.

• Remove the little cover from the back of the optical drive’s power connector.
• You should see four cables leading into the connector.

This big connector has the ability to generate 3 different voltages, 5v (slowest), 7v and 12v (fastest). Depending on your noise tolerance and the power and voltage rating of your fan, you may find any one of these three voltages suitable. This I will leave for you to experiment with.

Note, if your fan has three wires, one of them is unnecessary for this modification. You will have to determine which two wires (usually red and black) are the power wires and which one connects to the sensor.

The table below shows how to harness any of three voltages from the optical drive’s chunky 4 pin power connector. 

	Fan Wire 1 (Black)	Fan Wire 2 (Red or Yellow)
Fan at 5V	Molex Ground (Black)	Molex +5V (Red)
Fan at 7V	Molex +5V	Molex +12V (Yellow)
Fan at 12V	Molex Ground (Black)	Molex +12V (Yellow)

For example, to run the fan at 7V, connect the fan’s black wire to the +5V (Red) connection and the fan’s red/yellow wire to the +12V (Yellow) connection. You can connect the fan’s RPM wire directly up to the motherboard. Unfortunately, on the Mac, the wires are all black! Check the photo to confirm the voltages.

• Cut the power cables of the fan to a decent length, you won’t need the connector. You can discard the sensor wire on a three wire fan.
• Use a knife or other tool to push the cables strongly into the drive’s connector without damaging the metal “blades”. These blades should cut through the rubber insulation on the cable and create a connection with the copper wire itself.
• If the cable comes out, your fan will stop. This will be very difficult to spot later, unless you install a fan with an LED or other indicator, so confirm that the cable is tightly held before reassembling the computer. 

• Don’t forget to replace the plastic cover.

Putting things back together

• First the optical drive’s data and power cables.
• The optical drive’s holding screws.
• The power button’s wire connecting the top plate to the chassis.
• The chassis top plate with its 8 screws.
• Upturn the chassis carefully and pop out the handle
• Carefully return the chassis to the case, making sure not to catch anything, and push the handle in all the way until it clicks.
• Turn the computer over, connect it up and restart.
• Confirm the fan visually, by listening or by holding your hand over the top vent.

Congratulations, your Mac G4 Cube just got even cooler!

Upgrading iMac G4 to 640 MB.

The iMac G4 is unique, as far as I’m aware, in that it has two memory slots which take different types of memory. One slot is easily user accessible with nothing more than a screwdriver and takes a 133MHz laptop SO-DIMM, up to 512MB.

The other comes factory preinstalled (in this case with a 128 MB, 133MHz DIMM), but is much harder to access, requiring disassembly with a set of Torx (star) drivers.

Upgrading to 640MB, then, is a simple task requiring about 5 minutes.

You will need:

• A large area with soft padding to support the iMac in a lying down position.
• A small, cross-head (plus) driver.
• A branded 512 MB, 133 MHz, SO-DIMM for a laptop, preferably with a compatibility replacement guarantee, should things go wrong.

let’s get started:

• Turn the iMac on its side. Take special care not to scratch the screen or the computer’s plasic casing.
• Locate the four screws on the base and unscrew until loose.

• Carefully remove the beautifully crafted aluminium base plate, revealing the RAM slot.
• Ground yourself on something metal, like a metal door sash, a large metal desk or the kitchen sink.
• Carefully insert the 512MB RAM stick in the slot at about 30 degrees angle from the base. Push the long edge very firmly, sliding the chip into the slot. 

• Make sure the gold contacts are well in contact with the slots pins. When you are sure it is seated firmly, press down on the flat side of the chip until it is level with the base of the computer and the little tabs on either side clip into place.

• Make sure the chip is held firmly and the clips are properly clasping the chip.
• Replace the lid.

That’s it. Power on and check the Apple menu, and About This Mac to confirm the memory.

You should test the system over night with a memory checker. I recommend:

Rember by Kelly Computing

http://www.kelleycomputing.net:16080/rember/

You should now have an iMac with 640MB of RAM.