Experiences with a 2.7GHz G5

Figured that I would write up this post so that I can share my experiences with this G5. Since the case was a bit bent/broken when UPS shipped it, my original intention was to get another G5 of some sort for a case swap and possibly air-cooled so that I could throw those heatsinks on to see what the temps were like rather than using the LCS. To my surprise, my buddy hooked me up with another 2.7GHz as the supplier had a 1.8GHz DP, a 2.5GHz 2004 DP, and the 2.7GHz DP I bought. He took the 1.8 as it had various stickers for Disney Studios/ABC. We have yet to find out the mystery, but now I have 2 2.7GHz G5 macs! I don’t plan to do a case swap, and rather use the 2.7 with the bent case as a Mac Server or something (quite expensive for power! A single 1.6/1.8 would be much better suited as a file server).

But until I get the new 2.7GHz delivered, I have been using the bent case one for just over a week now. The experience has been off and on, and I will go through my journey to share as the 2.7 was intended to be a project, and that’s exactly what it was!

When I got it I ran it for a few minutes and the temps on the processors went up to 200*F which is really hot, granted I was testing 720p YouTube videos but it stayed in the 180*F range when I was done. I only used it for ten minutes until I decided to dust it out to remove the dust and tore down the LCS to rebuild it. I got the LCS running again on Saturday, after having a hell of a time fitting regular 3/8 fuel line over the fittings as I couldn’t find the right size of the inside diameter of the hose. I re-used the same O-Rings but flipped them so that way there would only be a little grove so coolant wouldn’t go everywhere. I was going to get the O-Rings later this week, I just wanted to use the mac to work on articles like this and doing some benchmarks.

Proceeding the rebuild, I stuck it back in the G5, and when I turned it on I would get 2 red lights on each processor card, and from what I could find the processors were overheating. When I put coolant in the system from reports I found it would take about 250ml to fill the system, and from the looks of it I only got 150ml or so in the system. I didn’t have proper tools so I was filling it through the CPU blocks, otherwise I would have done it from the top of the radiator but the fuel line was such a PITA to get off I didn’t bother. I did put AS5 on the CPUs as well. I took the system out quite a few times that day and on Sunday I got it to boot after getting more coolant in the system. Pressing the SMU button near the bottom RAM slots I got it to boot until it overheated and swapped the processors, which helped for heat as CPU0 always got the heat from the processor underneath it. I then did the Thermal Calibration, and ASD 2.5.7 would crash upon starting the calibration, while 2.5.8 worked great and took an hour and 40 minutes to finish.

One thing that really bothered me was when I opened just about any program the fans would rev up then back down. Not for long, but it did get annoying. Since there is no program to manually control the fans on a G5, I did the trick to edit the fans with a kext by adding 768 to each number in the kext. Fans were still there but not nearly as bad as what it was.

Then today I wanted to take the machine apart to finally get the leftover dust from the PSU and if there was some trapped behind the motherboard. When I did this, I took the waterblocks off the LCS and used a hose to suck up air out of the system while pouring in more coolant (this stuff tastes nasty and leaves a taste in your mouth for quite some time). However, I am happy to report that the machine runs much nicer and the fans for the CPUs is even less noticeable after I did the kext mod. CPU/A likes to stay from 168-174*F and CPU/B likes 158-166*F.


Now this thing is pretty stable with temps and noise, so I can now use it as a main machine for the next couple of days and will share my experiences! Keep an eye out for an update this weekend, plan to get lots done with PowerPC!

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