World's Fastest iMac G4 - 2 GHz iMac G4 CPU Upgrade

[cernorama]

indeed they are very hard to come by sadly, I am well aware of their scarcity

we have been aware of those 7448 SBCs for a good year or 2 now (its where the 7448 used in the iMac above originated from ) with confirmation that indeed we can make 7448s work @dosdude1 struck a deal with the ebay seller and he bought 6 of the units to pillage for 7448s.

indeed we spoke about the ebay listing

i also spoke to dosdude about the ones on alibaba but not sure how to come by them from there .. they have 1.6ghz and 1.7ghz ones for like 5.00/unit .. not sure how legit or easy it is to obtain from there

 

[0248294]

indeed we spoke about the ebay listing

i also spoke to dosdude about the ones on alibaba but not sure how to come by them from there .. they have 1.6ghz and 1.7ghz ones for like 5.00/unit .. not sure how legit or easy it is to obtain from there

I can tell you that the Alibaba ones use fake prices on the webpage to lure you in. Just for fun, I created an account with a throwaway email there, and inquired several sellers about the 7448 chips for sale. Prices ranged from $300 each to $800 each, then to $1000 each to $2000 each. Absolute insanity.

 

[cernorama]

I can tell you that the Alibaba ones use fake prices on the webpage to lure you in. Just for fun, I created an account with a throwaway email there, and inquired several sellers about the 7448 chips for sale. Prices ranged from $300 each to $800 each, then to $1000 each to $2000 each. Absolute insanity.

I figured something must be up

 

[DearthnVader]

So @dosdude1 and @LightBulbFun, did you ever figure patching later firmwares?

Daniel and I worked on a way to dump the ROM of a running machine:

http://macos9lives.com/smforum/index.php/topic,4295.0.html

It would be interesting to dump a patched firmware and compare it to the unpatched one, so we can see what, exactly, the patch does. Then maybe we can get it working on later firmwares.

 

[LightBulbFun]

So @dosdude1 and @LightBulbFun, did you ever figure patching later firmwares?

Daniel and I worked on a way to dump the ROM of a running machine:

http://macos9lives.com/smforum/index.php/topic,4295.0.html

It would be interesting to dump a patched firmware and compare it to the unpatched one, so we can see what, exactly, the patch does. Then maybe we can get it working on later firmwares.

Firmwares 4.8 and later are still being worked on

however I did a bit of sleuthing and found some info that let @dosdude1 compile a PPC Linux version of flashrom that can read and write some of the BootROMs in PPC macs so we have been able to dump some BootROMs that way

 

[DearthnVader]

Firmwares 4.8 and later are still being worked on

however I did a bit of sleuthing and found some info that let @dosdude1 compile a PPC Linux version of flashrom that can read and write some of the BootROMs in PPC macs so we have been able to dump some BootROMs that way

I'd be interested to know how to use flashrom too, maybe when you get time you can do a howto on the code changes needed, and what command line to feed to flashrom. I always found using that tool very confusing, and I don't think I ever was brave enough to properly use it, for fear of bricking a machine.

Cool work, and thanks to you and @dosdude1 for pushing these old system to the very limit.
[doublepost=1534252282][/doublepost]BTW, Mouser has 40 1.7Ghz mpc7448's in stock, sadly over $400 each.

 

[Eightbitgamer757]

well i found a 1.5ghz pbg4 for you

https://www.ebay.com/i/263679725747...&rk=7&rkt=30&sd=192617808164&itm=263679725747

 

[earlytv]

I have 2 early iMac G4 systems, 800mhz with pc133 or pc100 ram.
Will any of the cpu upgrades work on these? Which ones and how much to install in one system?

 

[dosdude1]

I have 2 early iMac G4 systems, 800mhz with pc133 or pc100 ram.
Will any of the cpu upgrades work on these? Which ones and how much to install in one system?

Those use 7455 CPUs, meaning the only plausible upgrade option would be a 7457. 7457s are very hard to find, though, and as such are very expensive, making an upgrade not really worth doing.

 

[caincha]

A bit off-topic but maybe I can get some help here
I bought a A1106 1.5ghz PowerBook for very cheap and decided to follow this guide ( https://www.overclock.net/forum/251-mac/1445164-ultimate-mac-overclocking.html ) and tried from 2 GHz backwards until I managed to get the PowerBook to boot on Safe Mode @ 1.83 GHz.
It has the A7447B CPU meaning it was probably under-clocked to 1.5 GHz?

Anyway the thing is: It only boots on safe mode otherwise it gets stuck on the boot screen and the wheel doesn’t spin.
And that’s when it boots at all sometimes it stays on the black screen beeping random codes - one, three, four times - on each boot...
Tried 1.75 GHz but won’t boot at all and 1.67 GHz boots on safe mode but gives grey screen on regular boot.
Tried another user account but no success. Oh and I seem unable to boot the install disk.

Any suggestions…?

 

[dosdude1]

A bit off-topic but maybe I can get some help here
I bought a A1106 1.5ghz PowerBook for very cheap and decided to follow this guide ( https://www.overclock.net/forum/251-mac/1445164-ultimate-mac-overclocking.html ) and tried from 2 GHz backwards until I managed to get the PowerBook to boot on Safe Mode @ 1.83 GHz.
It has the A7447B CPU meaning it was probably under-clocked to 1.5 GHz?

Anyway the thing is: It only boots on safe mode otherwise it gets stuck on the boot screen and the wheel doesn’t spin.
And that’s when it boots at all sometimes it stays on the black screen beeping random codes - one, three, four times - on each boot...
Tried 1.75 GHz but won’t boot at all and 1.67 GHz boots on safe mode but gives grey screen on regular boot.
Tried another user account but no success. Oh and I seem unable to boot the install disk.

Any suggestions…?

The GPU could be bad... Did it exhibit this issue before attempting to overclock it?

 

[caincha]

The GPU could be bad... Did it exhibit this issue before attempting to overclock it?

Nope it was all good before. I did install ATIccelerator though maybe I should try to uninstall it on Safe Boot and see what happens?
Oh I did got some copper shins with MX-4 to bridge the gap where there were some thermal pads before, could this be an issue…?

 

[dosdude1]

Nope it was all good before. I did install ATIccelerator though maybe I should try to uninstall it on Safe Boot and see what happens?
Oh I did got some copper shins with MX-4 to bridge the gap where there were some thermal pads before, could this be an issue…?

Yes... Put thermal pads where they're supposed to go. And yes, get ATIccelerator uninstalled.

 

[caincha]

Yes... Put thermal pads where they're supposed to go. And yes, get ATIccelerator uninstalled.

But wouldn't copper shins + MX-4 be better than thermal pads to transfer heat…?
Will uninstall ATceelerator first - it's easier than pulling the logic board out again
Thanks for the quick replies by the way

 

[LightBulbFun]

couple things worth mentioning

rabidz7 is a bit of a nut case so take whatever you find by him with a large pinch of salt.

as for your PB woes, first thing I would do is set it back to 1.5Ghz make sure it works fine at stock speeds then we can go from there.

 

[caincha]

couple things worth mentioning

rabidz7 is a bit of a nut case so take whatever you find by him with a large pinch of salt.

as for your PB woes, first thing I would do is set it back to 1.5Ghz make sure it works fine at stock speeds then we can go from there.

Hahaha yeah I've seem lots of his rants about PPC on several forums
About my PB the first thing I did was to do a fresh install and check everything beforehand. Then I started to play with the logic board - which lead me to where I am at the moment…
[doublepost=1537159510][/doublepost]Uninstalled ATIccelerator, still the same issues…
Noticed one thing though: the beeping codes only happens with the charger plugged in. When working on battery power it boots (to safe mode) every time.

And I forgot to post pictures so here they are

 

[LightBulbFun]

Hahaha yeah I've seem lots of his rants about PPC on several forums
About my PB the first thing I did was to do a fresh install and check everything beforehand. Then I started to play with the logic board - which lead me to where I am at the moment…
[doublepost=1537159510][/doublepost]Uninstalled ATIccelerator, still the same issues…
Noticed one thing though: the beeping codes only happens with the charger plugged in. When working on battery power it boots (to safe mode) every time.

And I forgot to post pictures so here they are

it may still be a overclock issue as when you run off battery the CPU clock speed gets throttled

I would put the system back to 1.5Ghz and make sure everything is still working.

also if it boots in safe mode at say 1.83Ghz run GeekBench 2.2.0 (or 2.2.7 if your in 10.5.8) and see if it finishes and post what score ya get.

should give us some insight as to whats going on, but I imagine to get stable at 1.83Ghz assuming your chip can do that speeds you would need to bump the core voltage up a notch or 2.

 

[caincha]

it may still be a overclock issue as when you run off battery
should give us some insight as to whats going on, but I imagine to get stable at 1.83Ghz assuming your chip can do that speeds you would need to bump the core voltage up a notch or 2.

I modded the vCore according to the info on that thread and is supposed to be @1.60v (from 1.30v).
I'm running Tiger and will try GeekBench
[doublepost=1537163937][/doublepost]GeekBench on Safe Mode
(battery)

(charger)

If it helps I also got this from the Open Firmware:

 

[LightBulbFun]

your scores are much lower then they should be for 1.83Ghz

I think the CPU is still stuck at Half DFS mode (917Mhz in this case)

when you try and boot up in non safe mode, try booting up in verbose mode and send a picture of where it hangs at assuming ya get a log.

also a video of some kind of the various Beeps would help.

 

[caincha]

Like I said it beeps 1, 3 and 4 times randomly.
And it did hung…

 

[LightBulbFun]

hmm the I2c errors are not good

and its unusual how its cut off at the bottom like that

have you tried some diffrent RAM sticks? and like i said try put it back to 1.5Ghz and see ya get any change

failing all of that you may have a bad motherboard (best guess is somethings taken out the I2c bus)

 

[caincha]

Yeah I saw those errors over there and knew it couldn't be good…
Where would the I2C bus be in the logic board?
I don't think the logic board itself is bad most likely I was the one who fecked it up. If I knew where to find the I2C bus I could try to see if it was something I did…
[doublepost=1537171963][/doublepost]I checked the diagram and… yeah the I2C BUS seems to connect to everything…
[doublepost=1537172186][/doublepost]What I'll do is to remove the logic board, clean it up all the way with isopropyl alcohol to remove every last drop of thermal paste and all then I'll re-check what I've done so far (from the diagram I'm suspecting I might've fecked the vCore).
Then get it back to 1.5ghz like suggested and see if it boots. If it doesn't then I'm pretty sure I can say it's dead so I'll sell online for parts…
But if it does boot then I'll start over from scratch

 

[caincha]

Haven’t had the time to get to it yet but I was thinking: the original voltage at the vCore should be precisely 1.385v if I remember correctly that means I haven’t upped to 1.6 but to 1.685v which is pretty much 1.7v and that could be proven to be too much..?
I’ve read that 1.83ghz could be achieved with stock voltage (I was aiming for 2ghz initially hence the vmod) so maybe the first step would be to get the vCore to stock and go from there before anything more labourious..?

 

[LightBulbFun]

Haven’t had the time to get to it yet but I was thinking: the original voltage at the vCore should be precisely 1.385v if I remember correctly that means I haven’t upped to 1.6 but to 1.685v which is pretty much 1.7v and that could be proven to be too much..?
I’ve read that 1.83ghz could be achieved with stock voltage (I was aiming for 2ghz initially hence the vmod) so maybe the first step would be to get the vCore to stock and go from there before anything more labourious..?

the Max Safe voltage for a 7447A is 1.6V so if you went above that you may well have fried your CPU.

I would set things back to stock and go from there.

 

[caincha]

the Max Safe voltage for a 7447A is 1.6V so if you went above that you may well have fried your CPU.

I would set things back to stock and go from there.

It hasn't fried it still boot and actually work - on Safe Mode but works.
Yeah I'll get the vCore back to stock and go from there. If everything is still the same I'll revert the O/C as well but then I don't see the point of trying to O/C again.
If it does work back to stock guess I'll rather leave it like that and try to buy the 1.67ghz Hi-Res in the future at least it has DDR2…