So I am kinda embarrassed to say that I have not marked the CPUs to identify which slot each one goes in. And I was wondering if someone could enlighten me to help me understand what would happen if I put them in the opposite slots? How do I tell if I have them in the right slots, or is there no issues at all?

Should be no issue at all. There are instances where if you have a single dead or faulty CPU, the computer will only work if the dead CPU is in one specific slot, so if you get no boot at all, swap them to the opposite positions. Run the Apple Hardware Test disk if you have issues.

>> phunguss said:

Should be no issue at all. There are instances where if you have a single dead or faulty CPU, the computer will only work if the dead CPU is in one specific slot, so if you get no boot at all, swap them to the opposite positions. Run the Apple Hardware Test disk if you have issues. Click to expand...

Thank you so much, I was getting really worried after reading that i should mark what cpu came from what slot. I was worried that something like a voltage difference would kill or damage one of them, like if one of them was wired up in a mirror or if it was just the same and simply didn't like a change in cpu between the slots, or if it only applied to the case of a dead or damaged CPU. I will also like to say thank you so much for your help and information it means a lot, but can I trouble you to ask for advice with creating a disc image for the Apple software that you mentioned? I have tried making apple boot discs before and it has only worked twice I believe three times at most and they were all usb sticks that were created using Rufus or belena etcher. So any help would be greatly valued.

>> Cyclone740 said:

Thank you so much, I was getting really worried after reading that i should mark what cpu came from what slot. I was worried that something like a voltage difference would kill or damage one of them, like if one of them was wired up in a mirror or if it was just the same and simply didn't like a change in cpu between the slots, or if it only applied to the case of a dead or damaged CPU. I will also like to say thank you so much for your help and information it means a lot, but can I trouble you to ask for advice with creating a disc image for the Apple software that you mentioned? I have tried making apple boot discs before and it has only worked twice I believe three times at most and they were all usb sticks that were created using Rufus or belena etcher. So any help would be greatly valued. Click to expand...

Look for Apple Service Diagnostics. There are different versions, some work on G5, some do not. May be more info in this thread.
Otherwise try the Macintosh Repository here. I don't recall if the G5 can boot it from USB or not, I think I burned the CD.

>> phunguss said:

Look for Apple Service Diagnostics. There are different versions, some work on G5, some do not. May be more info in this thread . Otherwise try the Macintosh Repository here . I don't recall if the G5 can boot it from USB or not, I think I burned the CD. Click to expand...

Thank you again so much, can I just ask if there is anything special I need to do when burning the CD? Like does it have to be a CD? And does it have to be made using a certain program? Amd does it need to be done on a mac or can it be done on Windows?

Again thank you for all your help, I am just hoping that I can get the LCS back together properly, as there doesn't seem to be any guide or instructions about doing it, with my version and from as far as I had to go.

>> Cyclone740 said:

Thank you again so much, can I just ask if there is anything special I need to do when burning the CD? Like does it have to be a CD? And does it have to be made using a certain program? Amd does it need to be done on a mac or can it be done on Windows? Again thank you for all your help, I am just hoping that I can get the LCS back together properly, as there doesn't seem to be any guide or instructions about doing it, with my version and from as far as I had to go. Click to expand...

The link I provided is a DMG, as well as this one... but if you have PowerISO, it can burn a mac DMG file on Windows. It does not need to be a CD, it could be a DVD, but it needs to be a format the that internal drive can read. Not all drives can read all media types.

>> phunguss said:

The link I provided is a DMG, as well as this one ... but if you have PowerISO, it can burn a mac DMG file on Windows. It does not need to be a CD, it could be a DVD, but it needs to be a format the that internal drive can read. Not all drives can read all media types. Click to expand...

Oh OK thank you so much, maybe that is one reason as to why it hasn't worked properly for me before.

Also do you know of anyone who has taken apart their dual pump LCS fully and then rebuilt it? I am just a little bit nervous about mucking up as I dont want to miss any screws or put them in the wrong places, and I want everything to go back together properly.

Any advice with that would be a great help. Thank you again.

>> Cyclone740 said:

Oh OK thank you so much, maybe that is one reason as to why it hasn't worked properly for me before. Also do you know of anyone who has taken apart their dual pump LCS fully and then rebuilt it? I am just a little bit nervous about mucking up as I dont want to miss any screws or put them in the wrong places, and I want everything to go back together properly. Any advice with that would be a great help. Thank you again. Click to expand...

Here is a detailed log of someone's LCS 1 (single pump) repair.
I know there are at least 3 different versions of the LCS. Some single pump, some dual.

>> phunguss said:

Here is a detailed log of someone's LCS 1 (single pump) repair. I know there are at least 3 different versions of the LCS. Some single pump, some dual. View attachment 21818 Click to expand...

Thank you so much for this.


Now I have a really insane question, if I do the plumbing right, could I run my system using only one pump?

Yes one of them just burnt the PCB and died on me.

MacRumors has a couple recent threads on converting a Quad G5 to air cooling.

>> joevt said:

MacRumors has a couple recent threads on converting a Quad G5 to air cooling. Click to expand...

Thanks, do you know if I could use two of the heatsinks from a 1.6Ghz or 1.8Ghz cpu, to air cool the quad?

>> Cyclone740 said:

Thanks, do you know if I could use two of the heatsinks from a 1.6Ghz or 1.8Ghz cpu, to air cool the quad? Click to expand...

I have no info regarding G5 air cooler compatibility with G5 liquid cooled CPUs.
I linked some air cooling threads at #9