Worth investigating or shall I break it for parts

[XKSTEVE]

Hi folks,

I was gifted as part of a IT clearance I did, an Apple Mac Pro 1.1 in amazing cosmetic condition but there is a problem.

The original owner said it just started rebooting after it had been on for a while. I removed the hard drive and fitted into her 5.1 MacPro so she has access to any data that might not have been backed up (it happens to even the best).

Anyways, got the 1.1 back to the workshop and fitted a new HDD and installed Lion on it but sure enough when it’s been on for a while it randomly restarts (took 3 attempts to install macOS).

My question therefore should I try and fix it? Or break it? Any ideas what can cause these machines to do this?

Seems a shame to break it and still possibly has a use even today.

your thoughts!

 

[phunguss]

I would try removing all but 1 stick of ram and see what happens. Possibly replace the thermal compound on the CPUs and the mid-board heatsink next to the PCIE slots. If you have access to an IR camera, you can see whats heating up. I have 2x 1,1, a 2,1 (1,1 firmware upgraded), and 2x 3,1.

FYI, The previous versions G5 had the opposite problem... they often don't boot until they warm up.

 

[XKSTEVE]

I would try removing all but 1 stick of ram and see what happens.

Thanks for the quick response. That’s a good idea to start and involves no time… Will these work with just 1 DIMM? I thought (maybe incorrectly) that they had to be in pairs (top 1,2 then bottom 1,2 -top 3,4 and finally bottom 3,4 with position 1 inner most near gold riser edge connector).or have I got my brain fuddled?

 

[phunguss]

Sorry, yeah, G5 will run with a single DIMM, but intel requires 2. OWC lists 1 in each if you are only using 2. But I have run them with 2 in either riser as well.

Two DIMMs (standard configuration)	One on the top memory card and one on the bottom card
Four DIMMsFour DIMMs	One pair on the top memory card and one pair on the bottom card
Six DIMMsSix DIMMs	Two pairs on the top memory card and one pair on the bottom card
Six DIMMsSix DIMMs	Two pairs on the top memory card and two pairs on the bottom card

https://eshop.macsales.com/Customiz...=install_videos/macpro/macpro_quicksheet.html

 

[XKSTEVE]

Thanks for the clarificatio.. I’ll pull the machine downstairs later and put it on the bench tomorrow and try with two DIMMs as per the data you provided. If it still reboots I will swap for the other pair. Hope it is just a simple DIMM failure.

 

[XKSTEVE]

Umm this is weird.
first off, thanks go out to @phunguss for suggesting memory as that seems to be where there is a Bus issue.

For clarity Riser A top, Riser B bottom DIMMs in riser A 1+2 and in riser B 3 and 4

Removed DIMMs 3 and 4 from riser b - machine runs fine
Swapped DIMMs 1 and 2 for 3 and 4 in Riser A - machine runs fine.
DIAGNOSIS: DIMMS OK?
Swapped riser A for riser B (A moved to bottom and B now top) with DIMMS 1 and 2 in riser B - machine runs fine.
DIAGNOSIS: Riser A and B ok?
moved riser B with DIMMs 1 and 2 to bottom and empty riser A to top - machine still ok.
Fully populated riser A with DIMMs 1, 2, 3 and 4 - machine runs fine. (Is there an issue running it this way?)
But machine will not work with DIMMS in both risers.
Solution? Put larger capacity DIMMs in one riser only.

Any advice very welcomed as I think it would be a shame to scrap this. I can get a replacement logic board here in the uk for about £40, is that the way to go.

Just as an aside- the machine used to be used in the original config that now exhibits the pro let almost daily.

 

[phunguss]

For clarity Riser A top, Riser B bottom DIMMs in riser A 1+2 and in riser B 3 and 4

So you are saying riser A had ram in slot 1+2 and riser B had ram in slots 3+4? The correct config should be both A+B with ram in 1+2 (closest to the edge connector).

 

[XKSTEVE]

So you are saying riser A had ram in slot 1+2 and riser B had ram in slots 3+4? The correct config should be both A+B with ram in 1+2 (closest to the edge connector).

Yes your pictures show the config I am using.

In my description DIMM 1, 2, 3 and 4 refer to the actual physical DIMM

Regardless of whether using RISER A or B DIMMS are in Pairs in the slots nearest the edge connector so RISER A is populated in Slot 1 and Slot 2 and Riser B is populated in Slot 1 and Slot 2.

Currently I am using it with Riser A populated with DIMM 1, 2, 3, 4 in Slots 1, 2, 3, and 4 and Riser B is Empty.

IMG_0443/4/5 Not working configuration but how I tested each board singularly with the other riser empty. (and yes the clips are open on Riser B it's just for reference and not used in service lol)
IMG_0446 How I am using it now and working perfectly but not to Apple recommendation.

I don't think it will work in the other slots (3 and 4 only) as the bus needs to see output from a preceding down? stream DIMMs in order to address the higher memory addresses to be allocated.??

These machines are stupidly quick - I am playing with Adobe CS4 and WOW.

 

[phunguss]

I recall reading a thread somewhere (or a @HrutkayMods video) that the 512MB DIMMs were rather flaky and it suggested NOT to use them. I will have to see if I saved that reference.

Edit: found the video

 

[XKSTEVE]

Yes that's always a possibility that they don't like being split across empty DIMM Slots.

Would be interest if you could find more info.

Currently seems very happy configured with Riser A fully populated and Riser B empty. but would be better with more memory obviously (not that I have any spare

 

[phunguss]

Found the video link from @HrutkayMods , it says 512MB and 1MB are flaky.

 

[XKSTEVE]

Found the video link from @HrutkayMods , it says 512MB and 1MB are flaky.

Great, thank you.

interesting video and seems mainly relates to newer operating systems. And was mentioned in another video on the subject.

My Mac pro 1.1 is not crashing or having a kernel panic. It just restarts and produces no bug report and does not even acknowledge that it restarted. So not sure what it is doing.

Used it most of last night running Adobe CS4 and it’s happy as… even with multiple applications running simultaneously. At the moment I think I’ll just leave it in this setup of Riser A full and Riser B empty.