G5 Quad: Core Temperature Disparity

[tevion5]

Being relatively new to my Quad, I have yet to learn EVERYTHING about it, although my enthusiasm for the machine has helped. I've added a second HDD, two 7800GT's, Leopard and Tiger, as well as multiple games and software packages. One of these included temperature monitor which I like to put in my menu, vainly displaying the temps of all four cores. I also used Onyx to install the Processor system preference panel, which is very cool indeed.

But one thing has been bugging me lately about my core temperature. Namely, core 2 (aka. Core B on Chip 1) always seems to be more than 20*C higher than other cores during direct usage, and around 10*C higher on idle. Most cores go up to 50*C or so, but core 2 flys up as far as 75*C. In fact I sometimes wonder when my fans burst into life, that if they are only doing so for that one damn core.

An idea of what I mean:

Do any Quad owners here have the same story? Is this normal?

 

[Intell]

One processor or core being higher than the others is somewhat normal on G5's, more common on liquid cooled models in particular. As the cooler coolant comes out the radiator, it goes into the first processor. It then goes into the second processor, while still having the first processor's heat in it. After the second processor, it moves to the radiator to start the process over again.

 

[tevion5]

One processor or core being higher than the others is somewhat normal on G5's, more common on liquid cooled models in particular. As the cooler coolant comes out the radiator, it goes into the first processor. It then goes into the second processor, while still having the first processor's heat in it. After the second processor, it moves to the radiator to start the process over again.

I suppose that makes sense alright. Just thought it strange when there is such a difference between two cores of the same chip.

 

[jbarley]

I have a G5 quad and my core temperatures also are always different by 10 or 15 degrees C, have been that way since I purchased it 3 years ago with no apparent problematic issues.

 

[Mnowell69]

..but what the OP is saying is that only 1 of his cores is way out, not one of his processors (as is always the case with QUADS). i do find this very strange and it could be down to a problem with whatever sensor reads the temperature on core 2. (no idea if it's part of the logic board or part of the processor)

 

[MagicBoy]

It's an on-die sensor on the 970MP. Odds are it's probably an iffy sensor.

 

[tevion5]

It's an on-die sensor on the 970MP. Odds are it's probably an iffy sensor.

If that is the case, then my fans are spinning up for no reason then. Just a bit annoying, but the high temps probably aren't true do no real damage is being done.

 

[LAHegarty]

Name of software?

An idea of what I mean:

Do any Quad owners here have the same story? Is this normal?

 

[eyoungren]

Name of software?

Either Temperature Monitors X (or Lite) or iStat Menus.

iStat Menus displays data in your menu bar. Version 2 is the last "free" version, but it has a memory leak with the clock (when additional clocks are added) that wasn't fixed until version 3.0 which is a paid version and Intel only.

Version 4 is the current version of iStats.

I have 1 and 2 and I can zip up Temperature Monitor if you want either of those.

 

[jbarley]

Either Temperature Monitors X (or Lite) or iStat Menus.

iStat Menus displays data in your menu bar. Version 2 is the last "free" version, but it has a memory leak with the clock (when additional clocks are added) that wasn't fixed until version 3.0 which is a paid version and Intel only.

Version 4 is the current version of iStats.

I have 1 and 2 and I can zip up Temperature Monitor if you want either of those.

Paid version yes, but there is a PPC version as you can see below.

 

[eyoungren]

Paid version yes, but there is a PPC version as you can see below.

View attachment 703611

Thank you James! Forgot about that.

 

[LAHegarty]

Thanks, I'll try both and make a choice.

 

[amagichnich]

It doesn't necessarily have to be a sensor error. On multicore systems one core is usually one 'primary' core (as seen by applications that can't make use of multiple cores) that's usually hotter than the rest.
The biggest difference I have seen on one of my windows machines was 17°C!
I don't have G5 and therefore can't proof that the same applies to G5 Macs

 

[Orizence]

On my DC 2.0 It always has a 7-8c difference between cores, it always seems to be like that.

 

[amagichnich]

But... 43 to 68 seems to be a bit much. Does anyone know how the cores are assigned in G5s? From the temps I assume core 1 and 3 are CPU1 and 2 and 4 are CPU2 - is that correct?