Ten years after their release and these Mac Pros are still a lot of fun to own and to work on. I have worked on a lot of original Mac Pro 1,1's and have managed to resurrect many from what was seemingly certain death. This last one, however, has me stumped.
I picked this up as a throw-in yesterday. It was reported by the seller/giver as "working sometimes". This reports itself as a Mac Pro 2.1 with two 3.0 Quad Core CPU's. The symptom is that it randomly reboots or sometimes goes into a boot loop chiming repeatedly.
I noticed that, when it reboots, the two "CPU Overheat" LED's are lit. So, I decided to take the thing apart and look at the CPU cooling situation. Right away, I noticed some differences from the 1,1's I had worked on previously... like that second screw holding the CPU fan assembly in place and the different location of one of the CPU sensor plugs (where both are along the left side of the heatsinks). Digging deeper, I noticed a type of black plastic material between the bottom of the CPU heatsinks and the motherboard. The CPU heatsinks also seemed to be glued on as they did not want to just pull off. Anyway, seeing how the thing was basically free, I got a spudger under one of the heatsinks and popped it off. I did the same with the other. Looking at the tops of the CPUs and the bottoms of the heatsinks I could see a shiny silver material on both along with a metal gasket on the bottom of the heatsinks. After some online searching, I surmised that this was the fabled "Krytox" system (although what it was doing on a 3GHz system, I don't understand since it was apparently only used on the 3.2GHz systems). I tried to get the silver stuff off but had very little success. I decided just to add some Arctic Silver and put everything back together. If did not help (nor did it seem to hurt). I can often boot the system and get a minute or two of stable operation before the mouse pointer freezes and the thing reboots itsels and the CPUs overheat and yadda yadda yadda.
Seeing that it's a ten year old system, what I think think I might have here is a Frankenmac... a Mac Pro that has had parts swapped in and out, perhaps a little willy-nilly. That might explain the system reporting the CPU's as 3.0GHz but with the Krytox system. I forgot the mention that the system is running (if that is the right word) El Capitan 10.11.6 with the 32-bit efi.boot file in the appropriate locations. Another complication is that I can't do much software sleuthing as the machine shuts after a minute or two of use and then I have to let it cool down before it will boot up again.
So, what I would like to do is replace the existing CPUs with a pair of 5150's I have lying around to see if the problem is with the CPUs. I also have to solve the heatsink situation. I thought I would simply try to wear the Krytox off the bottom of the CPUs using 2000 grit sandpaper and elbow grease. (I understand that the specialized solvents required to do this chemically are just crazy expensive.) I thought that I might then try to re-install them onto the 5150's with Arctic Silver and without the metal gaskets.
Can anyone give me some guidance with this?
Thanks in advance,
I picked this up as a throw-in yesterday. It was reported by the seller/giver as "working sometimes". This reports itself as a Mac Pro 2.1 with two 3.0 Quad Core CPU's. The symptom is that it randomly reboots or sometimes goes into a boot loop chiming repeatedly.
I noticed that, when it reboots, the two "CPU Overheat" LED's are lit. So, I decided to take the thing apart and look at the CPU cooling situation. Right away, I noticed some differences from the 1,1's I had worked on previously... like that second screw holding the CPU fan assembly in place and the different location of one of the CPU sensor plugs (where both are along the left side of the heatsinks). Digging deeper, I noticed a type of black plastic material between the bottom of the CPU heatsinks and the motherboard. The CPU heatsinks also seemed to be glued on as they did not want to just pull off. Anyway, seeing how the thing was basically free, I got a spudger under one of the heatsinks and popped it off. I did the same with the other. Looking at the tops of the CPUs and the bottoms of the heatsinks I could see a shiny silver material on both along with a metal gasket on the bottom of the heatsinks. After some online searching, I surmised that this was the fabled "Krytox" system (although what it was doing on a 3GHz system, I don't understand since it was apparently only used on the 3.2GHz systems). I tried to get the silver stuff off but had very little success. I decided just to add some Arctic Silver and put everything back together. If did not help (nor did it seem to hurt). I can often boot the system and get a minute or two of stable operation before the mouse pointer freezes and the thing reboots itsels and the CPUs overheat and yadda yadda yadda.
Seeing that it's a ten year old system, what I think think I might have here is a Frankenmac... a Mac Pro that has had parts swapped in and out, perhaps a little willy-nilly. That might explain the system reporting the CPU's as 3.0GHz but with the Krytox system. I forgot the mention that the system is running (if that is the right word) El Capitan 10.11.6 with the 32-bit efi.boot file in the appropriate locations. Another complication is that I can't do much software sleuthing as the machine shuts after a minute or two of use and then I have to let it cool down before it will boot up again.
So, what I would like to do is replace the existing CPUs with a pair of 5150's I have lying around to see if the problem is with the CPUs. I also have to solve the heatsink situation. I thought I would simply try to wear the Krytox off the bottom of the CPUs using 2000 grit sandpaper and elbow grease. (I understand that the specialized solvents required to do this chemically are just crazy expensive.) I thought that I might then try to re-install them onto the 5150's with Arctic Silver and without the metal gaskets.
Can anyone give me some guidance with this?
Thanks in advance,