this is a sort of follow on post from my first DIY G4 thread so I do recommend you check that out here: https://forums.macrumors.com/threads/making-a-g4-pismo-upgrade-at-home.2019269/
so following from the successful CPU Swap I had done on the PowerBook G3 Pismo card, I really wanted to fit a G4 to an iMac G3, the Problem i faced was finding a suitable iMac G3, now not all iMac G3s are compatible with G4 7400 and 7410 CPUs the only ones that are where the iMac,1 PowerMac2,1 and PowerMac2,2 these iMacs used normal 750s with backside L2 cache which the G4 7400 and 7410 where designed to be drop in replacements for.
Now I did have a PowerMac2,2 But it was a rare FlowerPower model at the time i did not want to risk that iMac incase something went wrong with the BGA CPU swap, so for a long time I kept my eyes peeled for a suitable iMac G3 but nothing suitable turned up and temptation got the better of me and i embarked on the journey that was upgrading my FlowerPower iMac G3 with a G4 CPU
sadly it did not go to plan, when I soldered the G4 onto the iMac Logic board the iMac would not POST at this point I had a close look at the CPU and saw 2 solder balls had bridged to each other, Now i had a couple options i could of lifted the chip and put a fresh 7410 or I could ask if a friend (max1zzz on 68k MLA) wanted to have a go at it as he had the equipment to reball existing 7410 (which would of meant not using a new 7410 if the only problem was bad BGA balls) (he also has better tools then i do which reduced the risk the board getting damaged during the BGA rework) and thankfully he agreed to have a go at it
so i sent the board off to him, lots of PMing between me and him later, we deduced that the original 7410 had died during the first CPU swap and once we determined that the Logic board was ok we attempted to swap in a Fresh 7410 CPU and lo and behold The iMac G3 Board fired up with the G4 at this point he sent the logic board back and i fitted it back into its iMac G3 body and the iMac fired up and quickly booted into the tiger image that was on the hard drive i was quite ecstatic to see it boot up it was good to have my iMac working again and this time with a G4 CPU!
now came some of the fun stuff with a G4 CPU now fitted I could install 10.5.8 leopard on an iMac G3 indeed it booted right up with no issues (yay for UMA/Uninorth)
I believe this is the only FlowerPower iMac G3 that has a G4 fitted as the US FlowerPower iMacs where not compatible with G4s so the companies that did offer G4 upgrade services did not accepted them (as all those companies where based in the US) it would also the first FlowerPower iMac Running 10.5.8 leopard
all in all its been quite the journey and in a way im happy it went wrong initially, as me and max1zzz exchanged quite a lot of interesting information to do with this and a few PowerPC Macs and its lead to some other cool ideas that i hope to attempt
overall it runs really nicely with the G4 CPU soldered on, i had a Full 100% CPU load going (spotlight indexing in leopard and then geekbench) for over id say 2 hours and it never crashed or anything during that ordeal, theres also a nice little speed boost thanks to the G4
and now for some pictures and a geekbench result https://browser.geekbench.com/geekbench2/view/2628797
this is just after i had lifted the old IBM PPC750L off of the logic board (I Have since figured out how to remove the plastic gasket thing on the CPU cleanly with out leaving any residue on the CPU)
and heres a shot of the board now with the MPC7410 soldered to the board by max1zzz
so following from the successful CPU Swap I had done on the PowerBook G3 Pismo card, I really wanted to fit a G4 to an iMac G3, the Problem i faced was finding a suitable iMac G3, now not all iMac G3s are compatible with G4 7400 and 7410 CPUs the only ones that are where the iMac,1 PowerMac2,1 and PowerMac2,2 these iMacs used normal 750s with backside L2 cache which the G4 7400 and 7410 where designed to be drop in replacements for.
Now I did have a PowerMac2,2 But it was a rare FlowerPower model at the time i did not want to risk that iMac incase something went wrong with the BGA CPU swap, so for a long time I kept my eyes peeled for a suitable iMac G3 but nothing suitable turned up and temptation got the better of me and i embarked on the journey that was upgrading my FlowerPower iMac G3 with a G4 CPU
sadly it did not go to plan, when I soldered the G4 onto the iMac Logic board the iMac would not POST at this point I had a close look at the CPU and saw 2 solder balls had bridged to each other, Now i had a couple options i could of lifted the chip and put a fresh 7410 or I could ask if a friend (max1zzz on 68k MLA) wanted to have a go at it as he had the equipment to reball existing 7410 (which would of meant not using a new 7410 if the only problem was bad BGA balls) (he also has better tools then i do which reduced the risk the board getting damaged during the BGA rework) and thankfully he agreed to have a go at it
so i sent the board off to him, lots of PMing between me and him later, we deduced that the original 7410 had died during the first CPU swap and once we determined that the Logic board was ok we attempted to swap in a Fresh 7410 CPU and lo and behold The iMac G3 Board fired up with the G4
at this point he sent the logic board back and i fitted it back into its iMac G3 body and the iMac fired up and quickly booted into the tiger image that was on the hard drive i was quite ecstatic to see it boot up it was good to have my iMac working again and this time with a G4 CPU! now came some of the fun stuff with a G4 CPU now fitted I could install 10.5.8 leopard on an iMac G3
indeed it booted right up with no issues (yay for UMA/Uninorth)I believe this is the only FlowerPower iMac G3 that has a G4 fitted as the US FlowerPower iMacs where not compatible with G4s so the companies that did offer G4 upgrade services did not accepted them (as all those companies where based in the US) it would also the first FlowerPower iMac Running 10.5.8 leopard
all in all its been quite the journey and in a way im happy it went wrong initially, as me and max1zzz exchanged quite a lot of interesting information to do with this and a few PowerPC Macs and its lead to some other cool ideas that i hope to attempt
overall it runs really nicely with the G4 CPU soldered on, i had a Full 100% CPU load going (spotlight indexing in leopard and then geekbench) for over id say 2 hours and it never crashed or anything during that ordeal, theres also a nice little speed boost thanks to the G4
and now for some pictures and a geekbench result
https://browser.geekbench.com/geekbench2/view/2628797
this is just after i had lifted the old IBM PPC750L off of the logic board (I Have since figured out how to remove the plastic gasket thing on the CPU cleanly with out leaving any residue on the CPU)
and heres a shot of the board now with the MPC7410 soldered to the board by max1zzz
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