[blakespot]

I have been reading the threads and watching Hardware Monitor hoping that my dual G5 2.5 is not running too hot. The CPU's max at around 88deg C (CPUA) and 84deg C (CPUB) under heavy load before the fans cool them back into the 70's for a while. Well, today I installed SETI@Home and put it into action w/ "Highest" CPU setting in Energy Saver.

CPU's were up there but I kept hearing a fan come on that didn't seem to jive w/ CPU temp fluctiation. I then noticed it corresponded with the Memory Controller temp swings. The Memory Controller jumps to about 85deg C and then the backside mobo blower kicks in loudly to cool it. This happens every 10-15 seconds or so in SETI@Home. Heats up - blower kicks in - cools down, repeat.

Is this behaviors others see? Is the Memory Controller rated to peak that hot, and often?

Thoughts?



blakespot

[incubusdaemon]

that would make sense to me, as I believe the memory controller isn't covered by the water cooling system that cools the CPUs.

As far as rated temperatures go, 85 seems pretty hot, but HDDs are typically rated to go to 80 or higher, so maybe it's not too bad. (i.e. I can only guess)

[Dennis the Phantom Menace]

The memory controller in my 2.0 G5 seems to be runing at twice the temp of the CPUs when idle.

[MattiMattMatt]

This happens every 10-15 seconds or so in SETI@Home. Heats up - blower kicks in - cools down, repeat.

Have you considered the possibility that this is not a response to heat build up in the Mac, but a successful reception of estraterrestrial communication?

[Maflynn]

Originally posted by blakespot:
This happens every 10-15 seconds or so in SETI@Home. Heats up - blower kicks in - cools down, repeat.

I saw this on my G5 2.0, so much so that I chose not to run seti@home and when with folding instead.

For whatever reason the U3 heat sensor (memory controller) heats up quickly with this app and the fans (on my 2.0) turn up for a while, then when the temp drops, the fans cycle down, but then the heat climbs back and well you get the picture.

Mike

[Big Mac]

The U3 Memory Controller Heatsink temperature has been a concern of mine. (970 DP 2.0 Rev B) Something made me pay attention to it, and I've been meaning to post on the subject. My average is between 159F and 161F, but I've seen it as high as 169F in recent days. ThermographX's comparison table shows that to be high, but the program has not been updated since July to reflect Rev B temperature reports. Perhaps everyone can post their average and max temperatures so that we can get a better understanding of the issue?

[d.fine]

I had the same fan speeding up in my Dual 2.0, but this has been fixed for me since 10.3.5 ...

[blakespot]

Originally posted by d.fine:
I had the same fan speeding up in my Dual 2.0, but this has been fixed for me since 10.3.5 ...

I don't know if "fixed" is the word. Looking at the temperature of the memory controller sensor, there is a clear need for the fans to ramp up when it spike to that temperature range. A "fix" in my opinion would be to leave the sped-up fan running for 30 seconds or so in case there is a pattern of heat spikes, rather than having it need to ramp up every few seconds.

If the blower did not speed up to respond to this temperature, it would be a problem indeed.



blakespot

[d.fine]

Originally posted by blakespot:
I don't know if "fixed" is the word. Looking at the temperature of the memory controller sensor, there is a clear need for the fans to ramp up when it spike to that temperature range. A "fix" in my opinion would be to leave the sped-up fan running for 30 seconds or so in case there is a pattern of heat spikes, rather than having it need to ramp up every few seconds.

If the blower did not speed up to respond to this temperature, it would be a problem indeed.

blakespot

You're right, I didn't explain my situation correctly. In my case when that fan sped up it usually stayed that way until I restarted the system. Was annoying and noisy as hell, even after the system being in sleep for hours on end, I'd wake it up and that fan would go full speed. Since 10.3.5 upgrade this problems hasn't happened at all, plus that fan hasn't sped up even for short periods of time.

[videian28]

blake I have the EXACT same issue with seti@home, I have yet to call applecare on it (but intend to)

it only happens in this program as far as I can see

[blakespot]

Originally posted by videian28:
blake I have the EXACT same issue with seti@home, I have yet to call applecare on it (but intend to)

it only happens in this program as far as I can see

But the things is... Why is it an AppleCare issue? Yes, the fan cycles up and then down over and over. It does this because the memory controller spikes up in heat every few seconds in SETI@Home based on what the code is doing. The rear motherboard blower kicks in to cool the memory controller. It's doing its job - and it does is successfully. (I have never had a thermal runaway.)

Apple could change the fan code to leave any fan that's sped up running at the increased speed for some longer period of time, in case you are in a cyclical pattern of chip heatup, but that would annoy others more, perhaps. What I'm saying is - there's no "problem" here. It's annoying that such audible cooling is needed to keep the machine cool under SETI@Home, but that's the way it is.

My only real concern here is wear and tear on that rear motherboard blower as it cycles over and over. Maybe that's not a concern I need to harbor. Dunno.


blakespot

[videian28]

mine kicks in around every 10 seconds, winds straight up and then back down...non stop as long as the program is running, as soon as I shut it off, it stops

something is not right, that is foolish



look here, this is a 6 hour test

http://homepage.mac.com/erikmichaeli...56F75811D8.jpg

[cczjct]

I had abnormal fan noise for a year, I've finally had my problems solved.
My G5 (a Dual 2.0) purchased October 2003, had it s power supply replaced in February, with a note back from the company saying the Drive Bay fan was noisy but they couldn't get a replacement. I contacted Apple but got given the run-around, and not having many other G5's to listen to I put up with the noise until September this year - when I installed a new G5 where I work (an uncommen experience)-it was nearly silent, I made up my mind to contact Apple again. It took me 45 minutes on the phone to get them to agree to replace the case, as the Drive bay fan is part of the external structure, if I returned it to the shop I bought it from Apple said they'd send a replacement case. I also used ThermographX to monitor the internal sensors, and found that my U3 heatsink, rarely if ever went below 128C (how accurate that reading was I don't know - except to say that occasionaly it fell to something like 55C).
I kept the sensor logs and sent them along woth my G5 back to the shop for repair.
I waited a month for the replacement case and a new logic board - am I glad I did. No noise at all now, the Drive bay fan is almost inaudible, but the the U3 heatsink temperature has never gone above 51C, the fans haven't yet kicked in at all (only on boot). All the other internal temeratures are down as well. So I suspect it was the logic board all along.
So don't give in, don't accept second best make them fix your G5 until it works properly.

[videian28]

hmm