Curious G5 quad "issue"

[Amishallin]

Not really sure what's going on so maybe someone has some ideas. This G5 had the "new blood" mod done to it quite some time ago and has been running fine on an almost daily basis since then with periodic maintenance to keep fluid full. I posted many images of my "journey" in the new blood mod thread if anyone's interested. Today I was compiling something from macports and noticed the "issue." Normally when in the "build" stage all 4 cores are at 100% usage and the temps hover around 64C with non-obnoxious fan noise. The machine is run at "highest" setting the the energy saver preference pane.

So the issue now is CPU A being around 64C and CPU B in the 50s while CPU A/B intake/exhaust/pump are seemingly in fail safe mode. The temps of CPU A both top out at 74C until the system catches up (the temps of both CPUs increase at the same rate). Prior to today the temps of both CPUs would top out at 65C. When the energy saver is set to "reduced" the temps of both CPUs drop about 10-15C with much reduced fan noise which is normal (temp drop is normal). When the CPU load drops off the temps drop rapidly back to idle (upper 30's-low 40's are normal). What's weird is at max power CPU A is at the "normal" temp (64C) and at idle CPU B is at normal temp (upper 30'sC). CPU A seems to just be about 10C hotter now in general even at idle. For the past year the temps have all been within 4C of each other and drop to the same idle temp.

I ran all open firmware diagnostics relating to fans/power and they all passed and sounded normally. Both CPUs even passed calibration 2x in the past hour. The poor thing seems abnormally normal. If anyone is curious the thermal paste used during rebuild was Thermal Grizzly Kryonaut Extreme on the CPUs and all other chips with a heatsink. Had some left over from building a PC. The fluid is still clear and there has always been a couple tiny bibbles in the intake tube on both pumps. They don't move at idle and wiggle faster as the pumps ramp up.

The only thing that changed hardware wise is the unplugging of the lower SSD that contains a Linux install. Got tired of Leopard asking what to do with it on every boot. There is no way that could of caused this even though it was the last thing done between shutting down the G5 yesterday and starting it up after work today.

Attached are some images: 100% usage highest energy setting, 100% usage reduced energy setting, 100% 1 core usage (don't ask it does what it wants) highest energy setting, and idle (CPU B is normal). These were all taken while building from source. As stated earlier the idle temps were reached before I could grab my phone.

Before someone says it... I don't compile code every day.

 

[Franklinstein]

Try opening iTunes or iMovie or some other Apple program in addition to macports when this happens. I'm curious if, like my air-cooled DP 2.7s, the system starts running the fans and drops temperature.

 

[Amishallin]

Think I went above and beyond what you asked for.

When I first turned it on there were no readings in istat menus for anything temp/power related (this is new). After doing the rebuild the stock G5 plate and air baffle no longer fit due the height of the pumps so I made something out of tape to trick the sensor into thinking the baffle was installed. After removing the tape (and putting it back) the sensors were all displaying more normal values. Deciding to have a little fun I just started opening programs, had activity monitor update at shortest interval, have it play against itself in chess and play music from CD. In the images with the clock you can get an idea how long time has passed while doing this. There are 2 images of compiling and playing music. 1 is at highest power and the other at reduced. Those images were taken when the computer reached a "steady state" with the temps/fans/pumps not changing for consistency. While compiling at high power and listening to music the temp topped out at 77C on CPU A core 1 and 78C on CPU A core 2 while CPU B was still in the upper 60s. It all settled down once the system caught up.

 

[Amishallin]

Have some bad news. After booting CPU A temps were in the upper 70sC and climbing and CPU B temps were in the upper 20sC while the system was quickly ramping up to panic mode. I checked the energy save settings and the performance was still set to reduced. Seconds after that the over temp LED for CPU A lit up with checkstop. After shutting it down I noticed the CPU A side of the radiator was quite warm as was the inlet/outlet of the pump and that goofy "Z" tube . I know the pump(s) still work because those little bubbles wiggle quite vigorously depending on pump speed.

Attached are some images. You can clearly see those bubbles by the pump inlet that never went away. There are also images of my clamp setup around the blocks for CPU A and B. The silicone and silicone tube are rated for temps far higher than this machine can ever produce. The hose was medical grade (made in the USA) and I had to make a minimum length purchase if I remember right. Didn't want any of that cheap Chinese garbage. Got the hose clamps and ear clamps from a local hardware store.

I'm not looking forward to it but i'll have to remove the cooler and do a deeper inspection... at some point. Gonna have to see about connecting my film scanner to my gaming PC in the meantime.