---------- Original message ---------- Subject: Re: MDD 867 vs 1.0 Date: Montag 27 September 2010N From: "Tina K." <pengu...@gmx.com> To: g3-5-list@googlegroups.com
> On 2010/09/26 22:50, Bequette Jeff wrote: > > I have 2 machines, both MDD, 1 an 867ghzdp the other a 1ghzdp. The 1ghz > > machine has a dead mother board. Can I swap the processors 1.0 the 867 > > machine? Or should I look at swapping the motherboards? > > Sometimes Apple used the very same CPUs and MBs on different speed rated > machines, the difference being the resistors on the MB. It might be > possible to 'overclock' the 867 board but you have to be good at > soldering on a circuit board and know exactly what you're doing. Perhaps > a replacement MB would be the safest way to go. True: the 867 has a 133 MHz system bus, the Dual-1 GHz a 167 MHz system bus. Simply swapping the processor daughter board won't work – as expected. MDD, FW800 and Xserve system bus speeds: 133 MHz: * 867 MHz Dual (MDD) * 1.0 GHz Single (FW800) * 1.0 GHz Single (Xserve) * 1.0 GHz Dual (Xserve) 167 MHz: * 1.0 GHz Dual (MDD) * 1.25 GHz Dual (MDD) * 1.25 GHz Dual (FW800) * 1.42 GHz Dual (FW800) * 1.25 GHz Single (MDD 2003) * 1.33 GHz Single (Xserve) * 1.33 GHz Dual (Xserve) Running the Dual-1 GHz processors on a 133 MHz system board will work alright, but since the multiplicator is set on the processor's daughter board, you'll get a Dual-800 MHz instead of a Dual-1 GHz system! The original multipiliers are: 6.0x 167 MHz = 1 GHz 6.5x 133 MHz = 867 MHz Now, you'll have the multiplier from a Dual-1.0 GHz in a 133 MHz system board: 6.0x 133 MHz = 800 MHz The processor is an easy swap. If the mainboard system bus speed is the same everything works as expected. E.g. you could easily swap the processor from an Dual-1.42 GHz FW800 model into a Dual-1.0 GHz MDD, with no soldering or anything. You only need the original heatsink, because they are made for the specific processor and ajusted to the heat it produces – never use a Dual-1.42 GHz processor card with a Dual-1.0 GHz heatsink – it will overheat your processors! If the system bus speed differs, and is lower after the swap (from a faster bus speed to a slower bus speed) you'll end up with a slower processor speed. Nothing wrong with that, if you can live with it or want it that way. The other way around will overclock and thus overheat your processor, so this is a not really a good choice to make. So, you might want to go the hard way and do some soldering on the system board – or the processor. You have two options: 1.) Make the 133 MHz system board to be a 167 MHz system board. This may or may not work, as it overclocks the system board. As Tina mentioned, some system boards were actually 167 MHz ready but Apple made them be 133 MHz since they were needed for the slower processors. In that case it will work. Otherwise… well, you may break some parts and that will break your now still working system board as well. Sorry, I don't know how to distingish a 133 MHz system board that is 167 MHz capable from one that isn't. But you may find something in the web about that. 2.) Make the processor run on a 133 MHz system bus by changing the multiplier on the processor daughter card. To get a Dual-1.0 GHz processor on a 133 MHz system board, you'll have to set the multiplier from 6.0 to 7.5: (Note that this is exactly the same as in an Xserve G4 1.0 GHz system, as it has a 133 MHz system bus by design.) 6.0x 167 MHz = 1 GHz 7.5x 133 MHz = 1 GHz To do that, set the correct PLLs on the processors daughter card. You should have a very close look at these links: http://homepage.mac.com/paul74/Multipliers.htm http://xlr8yourmac.com/systems/g4_mirrored_drive_doors/G4_MDD_CPU_Module.html http://macschrauber.de/3elektronik/3elektronik/mddxlr8.html (german) To be honest, it would be easiest to stick to the Dual 867 MHz system. Cheers, Andreas aka Mac User #330250 -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
