Getting my G5 ready for another decade

My PowerMac G5 is in quite a good shape, particularly when considering its rich history. I bought it in december 2009 from a freelance photographer, who was using it about four years. Sticker on the inside says, that this machine is a Apple Reconditioned Product, so it probably had some other owner(s) before it was reborn on 05/05/05. CPUs are PowerPC 970 (2.2), which is a pre-FX version, used in the first generation G5 Macs from late 2003. Motherboard however indentifies itself as PowerMac7,3 - a model which didn't use pre-FX CPUs, Apple just mixed during reconditioning whatever components available.
During my five years with G5, I had only one hardware problem: faulty power supply unit. I bought couple of replacement PSUs on eBay and since then everything is OK. But after reading Cameron's Long life computing, I decided to do something similar for my PowerMac.

My to-do list for G5 cleaning was following:
  • Remove as much dust as possible with canned air.
  • Apply new thermal paste on both CPU's.
  • Buy new heatsink for Radeon 9800Pro
It took me one evening to do the first two points and one sunday afternoon to do the last.

My PowerMac G5 with fans removed

Dismantling the PowerMac and removing CPUs is the easy part. I know, because I had to remove both CPUs, when I was swapping my PSU for a new one four years ago. You can find very good photo guides on iFixit.

CPU cooling system

The only part, which can be called "tricky" is unscrewing screws holding CPUs on the system board. PowerPC 970FX has TDP 48W for 2GHz clock at 65°C. FX CPUs are manufactured with 90nm process, my pre-FX CPUs are manufactured with 130nm process and they have no problem to double that consumption at the same temperature, when under heavy load. Heatsinks are big, maybe even a bit bigger than necessary and that means you need long phillips and torx screwdrivers.

CPU with heatsink

After you have both CPUs removed from the computer, it is a good idea to mark which one is CPU1 and which is CPU2. According to my previous screenshots, CPU2 was producing more heat than CPU1, after the surgery it's the CPU1 which has higher temperature. As as it seems that most of the time CPU1 is doing more work than CPU2, temperature difference is even bigger than before. I even consider to do all the work again and swap CPUs back.
CPU board

If removing CPUs from the computer or removing heatsinks from CPUs was easy, removing old thermal paste was a hell on earth. CPU itself is completely covered with some kind of transparent plastic, only the core is uncovered. Old degraded paste was everywhere under the plastic, so there was no other way how to clean the CPU than remove plastic with sharp knife and then give it a bath in isopropyl alcohol.

Checking whether CPU is fixed back in main board

After applying new non-metalic thermal paste to CPU cores and removing as much of the dust from the inside as possible, you have to do every previous step in the opposite way to get your Mac assembled. Just before tightening screws, that are holding CPUs with heatsinks on the system board, it is good to check, whether CPUs are sitting in sockets. The best way is to put your smartphone close to the system board and take a photo with flashlight on. Nothing can kill your Mac better than misplaced CPU.
Actic Accelero L2 PLUS
My Mac-flashed PC version of Radeon 9800 Pro had DIY cooler, I made from two broken PC VGA cards after original fan stopped working. What was supposed to be a hotfix for couple of days, was there almost two years. I bought Arctic Accelero L2 PLUS, because it has really broad support for various cards. Unfortunately 9800 Pro is too old even for this cooler, so I had to drill another pair of holes to fix it with screws and hex nuts to the card.
As fan connector on the card is different than all connectors included with the cooler, I had to solder solder yet another molex connector to the CD/DVD power branch. It already powers DVD drive, VGA card (PC version of 9800 requires aditional power, Mac version doesn't, why?) and now the fan, I hope it can stand it in the long term.

And that's it. I hope that I made my G5 ready for another decade of service. I will however watch CPU temperatures to see the difference between CPU1 and CPU2. Ten degrees should still be OK, but better safe than sorry.
Written by Logout | Thursday, October 02, 2014 | Permanent link | Comments: 5