From: sizeofcat@riseup.net   
      
   On 2025-11-02 13:57:52 +0000, Vela025 said:   
      
   > On 31/10/2025 10:27, sizeofcat wrote:   
   >>> You have exactly the same iMac as me (generation-wise, the 1st gen, not   
   >>> the 2nd gen called ALS or 3rd gen called iSight), mine is 17 inch (the   
   >>> smaller one). Well, I've removed everything including the logicboard,   
   >>> repasted the CPU, GPU and U3 chip using Noctua thermal paste, I've   
   >>> blown air through all the fans and checked if they work OK considering   
   >>> those are 20-years old bearings, and the temperature is exactly the   
   >>> same as before. It idles at 60degrees Celsius and goes to 70degrees max   
   >>> in continued full load (I've compiled my Firefox fork in one day and   
   >>> the temp stayed at 70 through all the ordeal). If your temp goes over   
   >>> 70 you should consider replacing the thermal pads with either new pads   
   >>> or thermal paste.   
   >>>   
   >>> As for being quiet, it's quiet until 65 degress and then the fans start   
   >>> going hardcore (but not like a quad G5 PowerMac, obviously). Thing is   
   >>> there will be very few things pushing mine to 70 degrees, and that's   
   >>> mostly either Macports rebuilding GCC or CMake, or me re- building my   
   >>> Firefox or Thunderbird forks. GCC 14 rebuild takes about 3 days, CMake   
   >>> takes about one a half. Or Sims 2.   
   >>>   
   >>> Removing the logic board for the 1st gen is piece of cake, so repasting   
   >>> the chips should be an easy job. But you need to remove the logic board   
   >>> from the case first, because the U3 chip is on the bottom side of the   
   >>> board, pressed against a copper sink and the thermal pad was more like   
   >>> thermal gunk (completely destroyed, unlike the CPU and GPU ones).   
   >>>   
   >>> Let me know if there is anything else I can help you with, I opened   
   >>> mine a few times and it doesn't have any more secrets to me. I think I   
   >>> have some inside photos somewhere, too.   
   >>   
   >> I've uploaded a front and back logicboard photo in case you've never see it.   
   >>   
   >> https://sizeof.cat/files/logic_board_front.jpg   
   >> and   
   >> https://sizeof.cat/files/logic_board_back.jpg   
   >>   
   >> The U3 chip is the one to the left, on the back side.   
   >>   
   > Thanks for that I really appreciate it, the photos will come in very   
   > useful along with your description. I checked it today and with Safari   
   > open at Macintosh garden and the temperature sensor program (as for   
   > some reason in Tiger there is no option to report the temperature in   
   > System Monitor?!) it's running at 39.5C which gives a groaning noise,   
   > the whine starts when the fans ramp up. When I have a bit of free time   
   > I'll take it apart and give it good clean and re-paste. I know every   
   > one goes bonkers about the caps in the G5 iMacs, but mine have never   
   > given me any trouble, are yours ok, or is it just the later G5s?   
   >   
   > Thanks again for all the info!   
      
   There are two types of capacitors inside the G5 iMacs, the "K" and the   
   "X" ones. When you look at the top of the cap, there is an etch which   
   resembles one of those letters. K caps never go bad, X caps might go   
   bad. But honestly I've never heard of caps blowing in an iMac G5, the   
   power source on the other hand it's proper shit.   
      
   No problem fren!   
   --   
   PGP ID: 0x4ED4000C90382C23D4178CB9EC61D381F2735495   
   Website: http://sizeof.cat   
   Desktop: iMac G5 PowerPC, 2GB RAM, 2004   
   Laptop: iBook G4 PowerPC, 1.5GB RAM, 2005   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)