Specifications

iMac G4

The purchase

I purchased this computer from a craigslist post for $60 without any accessories. It was a frustrating experience.

My email archives indicate that I emailed the seller for the first time on December 1st 2017, and after receiving no reply, again on December 4th. I offered to pay cash and pick up the iMac.

The post expired and was reposted in January. I emailed again on January 22nd and received no reply. On the 25th I had my partner email the seller, in case somehow just my emails were not making it through. To no surprise, there was no reply.

I'm not ever surprised to get no reply to a craigslist email. It's just the nature of the site.

But the listing kept expiring and getting reposted. This suggested that there was a human going through the effort to repost the listing every month. So maybe it's a scam, but what kind of scam would involve an ad for a 15 year old computer and a communication medium that provides zero identifying information about the target?

The iMac was reposted in February. I emailed February 9th and again on February 15th after the seller updated the listing. Still no replies.

At this point I gave up, but did occasionally notice that the poor iMac was consistently relisted each month. I wondered if anyone else had tried to contact the seller and had given up like I had.

For some reason I emailed the seller again in August 2018, and for reasons unknown to me he replied!

I suggested that I pick up the iMac on Saturday and the seller agreed but gave me no information on where to make the pickup. I asked, and gave my cell phone number in case that was a better way for him to communicate (since email didn't appear to be effective...). He replied and asked "What time are you thinking?" and informed me of the general area where he lives, near a hospital. There would need to be more email round-trips. Frustration mounts.

I told him 3pm but to please suggest a better time if that didn't work. No reply. Saturday arrives without confirmation of time or location. "Can you please text me, call me, or tell me where to show up at 3pm?" I asked at noon on Saturday, and he finally told me his address.

My partner and I drove 45 minutes to a sprawling apartment complex where he lives. We drove around and tried to understand the organization of the complex but it was a suburban nightmare. We managed to find the apartment and I knocked on the door. No answer. No signs of life even. The doorknob on the frontdoor had a key lockbox hanging from it, as if waiting for a realtor to arrive for a showing. Still without a better method of contacting the idiot, I emailed him and told him that we were where he told us to meet and that it doesn't look like the right address.

But then we realize that we went to the wrong apartment. We're happy to find that the correct apartment is just across the parking lot. I walk over and knock on the door.

At the same time, and for the only time ever, he replied in a timely manner and apologized for giving the wrong address. I didn't notice this email...

I knock on the door and for the hundredth time there's no reply. I wait a minute and knock again. This time a sleepy woman in a bathrobe cracks the door—I'd clearly just woken her up from a Saturday afternoon nap. "Hi, sorry, I'm here to pick up an iMac from craigslist", I tell her. "Oh, uh... John's not here now. I thought he was camping? Did you confirm the time?"

"Yeah, we said 3pm", I said.

"Weird, he told me he was going camping this weekend. Let me see if I can call him." WTF! At this point I had to remind myself that despite perhaps making a particularly bad choice in men that this poor lady whose nap I'd interrupted was not responsible for this disaster.

A few minute pass and she can't reach John on the phone. I apologize for bothering her and decide to give up.

I checked my phone and saw email the seller sent 5 minutes before with his correct address. I'm fuming.

We got back in the car and again tried to decipher the organization of this residential hellscape but quickly realized that either the new address cannot be right or we were in the wrong complex because the apartments are all numbered in the 7000s and he just gave us a 3000 street address.

Around this time I remember suggesting to my partner that the stories about "craigslist killers" were probably about people being murdered after they repeatedly gave the other party the wrong address.

Less than a minute passed before I receive a final email that reads:

7xxx!!!! Sorry

I practiced some breathing exercises as we arrived at the apartment and saw the iMac sitting on the front porch. My partner reminded me that I never had to see this person again so I might as well be nice. Strange how people can come to completely opposite conclusions from the same starting point...

Hiding my rage, I exited the car and said hello. A man in his early 40s (should be young enough to competently use email!) apologized for the confusion.

The iMac sat on a small table on the front stoop, powered on and showing a screensaver. The mouse and keyboard were not attached, and he said he didn't want to include them because he still uses them with his laptop. Yes, he still uses a one-button mouse. I tried to conclude this awful transaction as quickly as possible while we made small talk, with him mentioning that he's an ambulance driver at the nearby hospital. I gave him $60 and put the iMac in my trunk.

As I headed to the driver side door of my car to leave, I stopped and asked a knowing question: "So, have you been trying to sell it for long?" My partner, still in the car, covered her face with a hand.

"For a few months now I guess."

"Yeah", I said. "I've been emailing you for about 9 months."

He's confused, which seems to be the theme of the story. I suggested that if he searches his email for the name of the craigslist post he'll find my emails. "Oh, gosh" he says. "I just don't understand. Sometimes you get a reply and you see it and sometimes it goes to a thread", as if that was just another word for a black hole.

I shrugged and got in the car. We joked on the way home about how unlucky you would be to have your life in the hands of an ambulance driver who probably couldn't remember how to get back to the hospital across the road from his home.

Finally it was over.

The upgrades

The CPU

The stock CPU in the iMac G4 is a PowerPC 7445, built on a 180nm process. It has 256kB of on-die L2 cache.

I found a near post on the MacRumors forum about upgrading the BGA CPU in the iMac to a later model. Pretty neat. The thread mentioned that there's an even faster model, the PowerPC 7448 that is also compatible but that no one had yet tried it. The 7448 is a 90nm die-shrink with 1MB of L2 cache.

CPU 7445 7448
Frequency 1.25 GHz 1.7 GHz
L2 256 kB 1 MB
Process 180 nm 90 nm
Die size 106 mm² 58.44 mm²
Transistors 33 M 90 M

Naturally that meant that I needed to find such a CPU, which I did... on a Chinese auction site. I ended up paying something like $80 for it, more than I paid for the iMac, but this is the price of novelty.

The CPU arrived still attached to the remnants of whatever board had been its former home.

MC7448HX1700LD

The upgrade was performed by dosdude1 for a very reasonable price.

$ cat /proc/cpuinfo
processor       : 0
cpu             : 7448, altivec supported
clock           : 1833.333326MHz
revision        : 2.2 (pvr 8004 0202)
bogomips        : 83.66

timebase        : 41600571
platform        : PowerMac
model           : PowerMac6,1
machine         : PowerMac6,1
motherboard     : PowerMac6,1 MacRISC3 Power Macintosh
detected as     : 287 (Flat panel iMac)
pmac flags      : 00000010
pmac-generation : NewWorld
Memory          : 2048 MB

What's more, he made a YouTube video of the process!

Unfortunately the CPU was unstable at an overclock of 2.0GHz so he reduced the clock speed to 1.83GHz which has proven to be stable.

The fan

The stock fan in the iMac G4 is a Superred CHA9212DS-TF 92mm fan. I can't find specifications for it online but it is 12V/0.26A.

A friend 3D printed this iMac G4 bracket for the Artic F9 Pro fan. The Arctic F9 Pro is a very quiet fan with a fluid dynamic bearings. With just a little soldering, I attached it to the odd three-pin connector from the original fan.

Since the iMac G4 doesn't have any temperature sensors—at least that are visible to the operating system—I'm unsure why the fan connector has three pins. In fact, only two of the three pins are actually attached to the motherboard, so the fan must run at a constant speed even under Mac OS.

The hard drive

Using a SATA/IDE adapter, I replaced the spinning rust IDE drive with an 80GB SATA drive.


Pictures