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water cooled quad core 2.3ghgz g5

Discussion in 'PowerPC Macs' started by hansolo669, Nov 27, 2009.

  1. macrumors regular

    hello yes it is time for hansolo669's random carzy question:
    i want to take a motherbord from a quad core 2.5ghz powermac g5 and swich the procesers with 2 2.3ghz g5's add water cooling (trough the heat sinks or somthing) and have (in essance) a water cool quad core 2.3 ghz powermac g5 - the only of it kind (hopefully) :D
    questions, comments, concerns?
  2. macrumors 68020


    The question is: Will the logic board run the 2,3 GHz PPC970MP CPUs. Hard to tell. If it does it would be a nice project. The only thing I don't like is the water cooling. If you do that you can stay with the 2,5 GHz PPC970MP CPUs that belong to that logic board.

    I guess you need to check in the late 2005 G5 manual if the logic board part numbers were the same for the 2,3 and 2,5 MHz versions.
  3. macrumors regular

    shouldent the cpus work aslong as the bus speeds are the same?
    also the point of adding the water cooling is that i dont entierly trust apples water cooling soloution and this way i know how it works so i can fix it :D

    this will(hopfully) be a nice but expensive project as i will have to buy pretty much everything to build this:p:apple:
  4. macrumors regular

    ok well this faild befor it started:(
    on this page: http://www.everymac.com/systems/app...een-late-2005-dual-quad-core-powermac-g5.html :it states that the 2.3 ghz has a 1.15 ghz bus and the 2.5 quad has a 1.25 ghz bus - this diffrence wold likle mean that the 2.3 proc wold fry itself trying to matchitself to the bus speed.

    or i might just be barking up the wrong tree... if what i said is false then dont hesitate to let me know...relly i mean it
  5. macrumors 601


    I'd find the quad G5 and replace it with the heatsinks off the 2.3 :). That way you loose the water cooling :)
  6. macrumors 65816


    But the question is, does it blend? I mean, do the fans have similar enough connections to work in the Quad model? And it'd run hotter, but a tradeoffs a tradeoff....
  7. macrumors 68020


    No way the heat sink fits. The 2,3 is a single CPU heat sink. It is way too big to fit twice in the space.

    I would not be too much worried about the FSB speed. The memory speed adjusts itself to half the CPU speed. I once exchanged 1,8 GHz CPUs with 2,0 GHz CPUs and it worked out without problems. In that case Apple had used the same logic board for both CPU types. As I said earlier for that to work you have to make sure the 2,3 and 2,5 had the same logic board.
  8. macrumors 68000

    Jason Beck

    Size matters.
  9. macrumors regular

    ahh i see. thank you now becasue of the closness i think the motherbords should be the same but i will check. dont you just love apple:D
  10. macrumors 65816


    Liquid cooling is crap. The ideal option would be to get rid of the water entirely and use the air heatsinks from a dual CPU 2.3 G5.
  11. macrumors 68020


    The dual air heat sinks are too small for the heat capacity, hence the size of the single CPU dual core heat sink of the 2,3 GHz PPC970MC.
  12. macrumors 65816


    Only if you're running the CPUs at 100% all the time.

    The fans will get a little noisy but it won't have a problem handling them.
  13. macrumors G5

    Sun Baked

    The FSB is set at 1/2 to 1/3 of the CPU speed.

    This isn't the problem, the problem is the programming Apple does to set all the speeds.

    Nobody really ever figured it out, and were able to swap CPUs to anything other that what came with the machine ... and even that requires a special DVD in order to acclimate the CPUs to the machine and prevent the fans from running full blast all the time.


    aka, these aren't your mothers CPUs, they are extremely complex beasts that got huge companies excited and then they immediately walked away when they found out how complex and expensive they are to work with.
  14. macrumors 68020


    You obviously did not read the thread before posting. I have exchanged June 2004 1,8 GHz CPUs with 2,0 GHz CPU successfully. No problem whatsoever. You just have to do the thermal calibration which was 25€ at the next AASP.

    I would not run the PPC790MC with under sized heat sinks though. All PPC790 chips past 2003 - basically all FX and MC - with 90 nm Strained Silicon Directly on Insulator (SSDOI) process have problems with heat cycles. Galvanic problems with this new process causes premature CPU failures. Running these chips hot obviously doesn't help with the problem.
  15. macrumors G5

    Sun Baked

    Congrats on using CPUs from different generations. Should have switched to the multi core CPUs. Most of the stories I saw was with people having problems swapping CPUs from different motherboards.

    Sorry if I thought that only CPUs that Apple used in the same machine/motherboards would work.

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