CPU card from G4 MDD DP 1.42GHz (FW800) not working in G4 MDD DP 1.0GHz (FW400)

[dead]

Hi Folks,

I've owned a G4 MDD DP 1.0GHz for a while now (one of the models that can boot into OS9) and I've always wanted to upgrade the processor with the DP 1.25GHz and overclock it to 1.5GHz.

Anyway, the opportunity to buy an MDD with the DP 1.42GHz (FW 800) came up and I jumped at it as I thought I could simply overclock it to 1.5GHz and put it (plus the copper heatsink!) into my older DP 1.0GHz machine.

So... I overclocked the 1.42GHz to 1.5GHz and it tested fine in the FW800 tower. But when I took it out and put it in my older machine (the 1.0GHz tower), the computer wouldn't boot.

I tried fitting the processor card several times (thinking that maybe I hadn't seated the card properly) but each time the machine didn't boot.

Both MDDs - the DP 1.42 GHz and DP 1.0 GHz - have the same System Bus Speed (167Mhz), so I thought the processor cards would be compatible.

Has anyone tried the above? Do the cards from the FW800 MDDs work in the earlier models that can boot to OS9?

Many thanks

[reader50]

Note that it's easy to get OS 9 booting on the FW800 models. They have downloads here for that. There's no magic reason why you must use the dual 1.0 instead of the FW800 model.

[FdB]

Yes. See this for more info:
http://macos9lives.com/smforum/index.php/topic,3705.msg24568.html#msg24568

And, you might put your 1.0 GHz CPU back in your 1.0 GHz machine to test if that still works.
(Just in case there's something else that you might be missing... or "shook" loose during transfer.)

[dead]

And, you might put your 1.0 GHz CPU back in your 1.0 GHz machine to test if that still works.
(Just in case there's something else that you might be missing... or "shook" loose during transfer.)

Yes, the 1.0 GHz works fine when it's put back in so it's a mystery.

[MacTron]

It's a really weird...
The 1.42 works perfectly in the FW400.

[GaryN]

Logically, this looks pretty simple.
MDD CPU cards are totally interchangeable.
The swap we're talking about here has been done many, many times and proven to work.
The only other variable you've introduced is the overclocking.
I suggest you restore the card to 1.42GHz and test again. Whether it "should" work overclocked or not is irrelevant; this is how you troubleshoot.

Also, you didn't say exactly where the boot fails. Can you try booting it in verbose mode? Maybe there's a clue there.

[dead]

Also, you didn't say exactly where the boot fails. Can you try booting it in verbose mode? Maybe there's a clue there.

The Mac turns on and chimes but then nothing after that. No noise of the hard drives. Nothing displaying on the monitor.

I tried to boot into verbose mode but it doesn't do it. Just blank screen.

I guess I'll put it back to 1.42GHz like you suggest and see if that helps.

Thanks

[dead]

I put the processor back to 1.42GHz but it still doesn't work in the FW400 tower.

So I can confirm in my case the 1.42GHz DP (FW800) processor card doesn't work in a 1.0GHz DP (FW400) MDD.

I've returned the 1.42GHz and the 1.0GHz cards back to the original machines they came from and they work fine.

[reader50]

A stupid question, did you press the PMU reset button on the FW400 after swapping the CPU? It's a mini-button on the forward edge of the board, near the ATA-66 connector.

[dead]

A stupid question, did you press the PMU reset button on the FW400 after swapping the CPU?

Yes, I did try the PMU reset button but the same thing happens. The Mac starts and it chimes and you hear the fans, but that's it.

I'm convinced the 1.42GHz DP card will not work in my FW400.

[GaryN]

Well, the only thing left, at least the only thing I can think of, is a firmware issue.
I'm not qualified to hack that, but there should be some checking you can do in Open Firmware.

Anybody?

[refinery]

possibly firmware?

i have a FW400 DP 1.0 which I upgraded to 1.42 without issue and has been running for years. that copper heatsink is so incredibly nice.