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Apple Fan 2008

macrumors 65816
Original poster
May 17, 2021
1,450
3,542
Florida, USA 🇺🇸

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But the early 2005 PM 7,2 used a 970fx.

No. The early 2005 was a PowerMac7,3 and relied on a different daughtercard/logic board/Open Firmware setup than the PowerMac7,2 of 2003.

It may be possible, say, to try a 2.7GHz PPC970fx CPU assembly in the mid-2004 PowerMac7,3, but nothing from prior to the mid-2004s did the PPC970fx see use.

Note: the above reference to early 2005 G5s is incorrect. This is the correct info for the base model early 2005 PowerMac7,3.
 

ifrit05

macrumors 6502a
Dec 23, 2013
548
385
Near Detroit, MI. USA
If you are brave enough I'm pretty sure the 7,2 and the 7,3 models share the same case design. You could (in theory) swap out the logic board in the 7,2 for a 7,3 logic board and install single/dual 2.0/2.3/2.5/2.7 970fx CPUs in it. I'm not too sure about power requirements though, you may need to swap out the PSU for that.
 
I just acquired a Dual-Core G5 2.0. I'm on the fence about getting a Dual CPU capable logic board to upgrade it to a Quad 2.3 (2.5 seems like it is unobtanium ATM.)

Yah, I’ve long poo-poohed the prospect of buying a quad-core G5 (it’s mostly a trophy piece these days, insofar as the price premium on them, for a lot of folks [who aren’t actually or actively using them on projects, such as SL-PPC or compiling Mozilla browsers], and I still have a hydro bill to pay each month).

I’m constantly looking out locally for a dual-core 2.3, which will still deliver a jump in performance over my mid-’04 dual 2.0. It also has almost everything the quad-core has — the eight DDR2 slots, the PCIe bus, the PPC970mp CPU, and the IBM-engineered main board — without needing to tap a special line to our nearby nuclear power plant.
 
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Apple Fan 2008

macrumors 65816
Original poster
May 17, 2021
1,450
3,542
Florida, USA 🇺🇸

AphoticD

macrumors 68020
Feb 17, 2017
2,283
3,462
A very good question. As others have stated, I wouldn't count on the 7,2 from 2003 being compatible with the 970fx CPUs from the 2005 7,3 model - but I can't say for sure, as I haven't tried this myself and I have not held these two CPUs side by side to determine if they are physically a match or not. So, buying the parts expecting this to work would be a gamble.

Around 2017, I performed a 2003 7,2 DP 1.8GHz > DP 2.0GHz upgrade and a Late 2005 11,2 DC 2.0GHz > DC 2.3GHz. Both upgrades provided a decent enough jump to make the exercise worthwhile.

The 2.3 DC ran great (calibrated perfectly, ran cool and quiet) for about 4 more years after this upgrade, until eventually, bank by bank it lost the capacity to use memory modules (of any spec). A few months back I completely decomissioned that G5, and it's role was re-assigned to an existing C2D 2.0GHz 2009 Mac mini with 6GB of RAM and a 7200rpm 500GB spinner.

The charming little incognito mini blends perfectly with my PowerPC hardware, runs Leopard natively and handles practically all the same apps the G5 did (Pro Tools LE + Ableton Live DAWs, Propellerheads Reason, and a ton of Native Instruments plugins, FX VSTs, etc) - although not PowerPC, it was a perfect "cross-grade" from the G5. The lower-spec C2D actually performs notably faster than the G5 did, with far more efficieny of power and is practically silent - plus it didn't cost me anything to dust the mini off and migrate the G5's HDD to the mini to get back up and running with all the same software config.

So energy consumption of this unit went from around 250 - 300w/hour to ~12w/hour for the same software setup.

Nothing against the G5. I have 4 of them (incuding the failed DC 2.3) which unfortunately get next to no run time. I am currently posting from my 12" PowerBook G4 though - so I haven't forsaken my PowerPC roots just yet :D

And I still have a (noisy) Quad 2.5GHz Late '05 G5, which refuses to calibrate, despite all my efforts to service the liquid cooling system, renew thermal paste, etc. I will get to this one day. Maybe I could source another 2.0GHz DC CPU and try the air-cooling "downgrade" as others have suggested to give it a chance to calibrate, stay cool and quiet.
 
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