G4 MDD and FW800 CPU compatibility

[lcdswat]

Hi there!
I have the powermac G4 MDD 1.25DP FW800 with broken logicboard and I want to buy another mac to repair my computer, but I didnt find exacty my model of it. But I have found an MDD 1.25 model (not FW800) which works pretty fine.
So I have a question – can I place my dual CPU board to a 1.25 MDD model? If answer is "Yes" I can just buy this MDD mac and upgrade CPU from my FW800 model, right?

Here is the links for full mac specs (everymac.com):
My broken mac – http://www.everymac.com/systems/apple/powermac_g4/specs/powermac_g4_1.25_dp_mdd_fw800.html
Mac that I found – http://www.everymac.com/systems/apple/powermac_g4/specs/powermac_g4_1.25_mdd.html


Thanks for your reply.

 

[0248294]

Yes, you can. The Single Processor 1.25GHz model already has the System Bus Clockspeed set at 167MHz, so a 1,25GHz Dual Processor board will run at full speed and will just be a drop-in replacement.

 

[lcdswat]

Thanks for the answer! I have order an MDD PM so after the installation of the CPU I will write in this thread how it went.

 

[lcdswat]

Yesterday I swapped CPU board from FW800 to MDD and it works very well. The temperature is probably high, some about 58–59 Celsius degrees in normal usage. Or maybe this is good temperature?
P.S. Fan sound is SO annoying... i will look for some mods to make it quieter.

 

[jbarley]

Check out my PS fan mod here, starts at post #11, quiet as a mouse.

 

[for this]

Yesterday I swapped CPU board from FW800 to MDD and it works very well. The temperature is probably high, some about 58–59 Celsius degrees in normal usage. Or maybe this is good temperature?
P.S. Fan sound is SO annoying... i will look for some mods to make it quieter.

58-59c is not a good range for MDDs. The upper limit for their CPUs is just 62c. I would try redoing the thermal paste and adding more fans. Mine is now idle at 55.6-56.0c with 31c room temperature (Arctic Cooling MX-2 and 3 more fans—2 beside the heat sink blowing out of the back and 1 PCI slot fan).

 

[lcdswat]

58-59c is not a good range for MDDs. The upper limit for their CPUs is just 62c. I would try redoing the thermal paste and adding more fans. Mine is now idle at 55.6-56.0c with 31c room temperature (Arctic Cooling MX-2 and 3 more fans—2 beside the heat sink blowing out of the back and 1 PCI slot fan).

Actually now I'm using Zalman STG-2 thermal paste, and planning to place two little fans behind of heatsink (like your config). I just looking for compatibility one. There also two HDD's behind heatsink with system RAID, maybe they are warms CPU's a little bit to. I have downloaded iStat Pro for system monitoring and it shows 42C degrees on the HDD's. Maybe it's just fake
I also have kernel panics two time on day, not sure why. Can it be because CPU swapping? I think i should to reset PMU, replace battery and run some stress-test applications to check system stability.

 

[for this]

I once had two drives in the back drive bay. Their temperatures were about the same as yours. So I think it's probably not lying.