Is it possible to upgrade the dual CPUs in a 450 MHz Graphite Gigabit Ethernet Power Mac G4?

[wry]

Hey all, I recently acquired a 2000 Graphite Gigabit Ethernet Power Mac G4 from an estate sale, and it came with the mouse, keyboard, monitor, and everything. It’s in very good condition, but the thing doesn’t power on right now because the clock battery inside of it is dead, so I’ve ordered a new one.

450 MHz is a little slow by today’s standards, and I was wondering if I could somehow upgrade the CPUs on the daughterboard, because it’s cheaper to do that and solder them on than it is to buy one of the discontinued aftermarket boards. So I did a little research… and I think my options are limited, because looking on NXP’s site for the MPC7447A and others, it says “This pinout is not compatible with the MPC750, MPC7400, or MPC7410.”

Then I looked into CPU cards from other dual-CPU G4 models, but I’m wondering if they’ll be compatible or not.

So what are my options?

 

[eyoungren]

You can…

• Find an aftermarket CPU (Sonnet, MaxPower, Newertech, GigaDesigns and others). The most powerful CPU sold was a single processor 2.0Ghz by Newertech.

• Upgrade to the max GPU Apple made that is compatible with your system bus. There may be some modification required depending on the CPU.

• Futz around looking to solder a new one on. That's going to require skills and some serious technical knowledge about the G4.

In no case are you going to do better than a G4 processor. These are not modern Macs and even when upgraded, it is not necessarily a benefit. Despite having a 1.8Ghz dual processor in my Quicksilver, browsing the web and hitting up Youtube involved a lot of workarounds. And that was 2015-2016.

If your intent is mainly to use period software and tasks that this Mac was capable of during its time than you'll be fine. You just aren't going to be running a modern OS and modern software on it.

 

[ervus]

Yes, it is possible to upgrade that CPU. It's possible to solder on slightly newer chips. It's possible to use a stock CPU board from some of the later G4 computers. There are custom and aftermarket upgrade options as well.

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First, I would suggest figuring out why it won't boot. The battery should not cause this.

 

[wry]

First, I would suggest figuring out why it won't boot. The battery should not cause this.

By “boot” I meant “even power on at all”, which it doesn’t. So I ordered some replacement batteries, the one I took out had fallen below it’s 3.6v rating and was only putting out 3mA of current when it should have been 100mA.

 

[TheShortTimer]

By “boot” I meant “even power on at all”, which it doesn’t. So I ordered some replacement batteries, the one I took out had fallen below it’s 3.6v rating and was only putting out 3mA of current when it should have been 100mA.

As @ervus has pointed out, the PRAM battery, whilst important, should not prevent the computer from powering on. Which means that its PSU could be shot.

 

[lepidotós]

The PRAM battery doesn't affect booting -- my G4 Sawtooth (not a Gigabit, but it uses the same motherboard design besides the additional internal FW and USB ports) boots and I've ripped that battery right out completely. It's likely a power supply issue, the power supplies in the Gigabit Ethernets weren't the most amazingly reliable things. You can either try getting it repaired for $90, getting a second one on eBay, or buying an adapter that converts a standard ATX power supply to Gigabit standards -- plus, with that one, you can get an 80+ Bronze or Gold power supply and save on your energy costs and heat output.
Soldering a new CPU will only get you as far as the 7410, which was just a die-shrink of the 7400 -- the 7450 and onward use a different pin layout and, for the 745x series a different number of pins (483), so it's not a simple solder-on job. You should be able to OC to 600, though, which I guarantee with two processors will be enough. A single 867 is enough to watch YouTube, and my single 450, while it definitely struggles, still manages to get a choppy mess with sound going. A rule of thumb I heard here is that the second processor adds about an effective 400MHz bump, so a dual 600 would be roughly on par with a single 1000. The processor cards for all G4s between the Sawtooth and Quicksilver 2002 are compatible with each other, but PCI Graphics and MDD are unique. However, the Sawtooth and GE use a 100MHz bus while later computers use a 133MHz bus, so your CPU speed will change too.
And then there's stuff you can do like OCing the bus to 133, but that might limit you to 1GB RAM if you use high density sticks, so it's generally a tinker project for now since if you only get 1GB RAM, you'd be better off with a Digital Audio or Quicksilver. Something you can do is get a card with Quartz Extreme and Core Image (which, for the Gigabit, basically means a Radeon 9550, 9600, 9700, or 9800 series), and that will take a lot of the load of rendering the desktop off the CPU and put it onto the GPU when using Tiger and Leopard -- but at the expense of lacking any driver support at all in Mac OS 9.
Also, there are lighter-weight OS options like OpenBSD and Void Linux if you're willing to jump headfirst into that world.​

 

[Wild Hare]

Out of curiosity, have you tried a PMU reset?


Screenshot instructions borrowed from a friend.

(It's worth a try.)

 

[wry]

Out of curiosity, have you tried a PMU reset?

View attachment 1954799
Screenshot instructions borrowed from a friend.

(It's worth a try.)

It's likely a power supply issue, the power supplies in the Gigabit Ethernets weren't the most amazingly reliable things.​

Yeah I went and took a multimeter to the contacts on the 22-pin ATX cable while it was plugged in, got no readings. Probed different contacts and still got nothing.

 

[Amethyst1]

Yeah I went and took a multimeter to the contacts on the 22-pin ATX cable while it was plugged in, got no readings. Probed different contacts and still got nothing.

If the PSU behaves like an ATX one, you’ll get (virtually) no readings until the PSU is turned on by the logic board. Look up the pinout to see which pins need to be bridged in order to turn on the PSU.

 

[wry]

If the PSU behaves like an ATX one, you’ll get (virtually) no readings until the PSU is turned on by the logic board. Look up the pinout to see which pins need to be bridged in order to turn on the PSU.

I did, and I tried to short pins 15 and 16; no luck. Opened the thing up and something looks like it’s melted or burnt off.