CPU temperature in "Idle" when on battery / AC

Hi,

I just turned into a Mac user for some days ago. Really like Leopard etc and the Macbook 5.1 is also really nice. But nothing is perfect..

The left upper corner on my Macbook is quite hot for being a /laptop/. At the moment I do not want to sit with my new computer in my lap for more than 15 minutes (feels like sitting whit a frying pan in ones lap). I guess the that the CPU is located in the left corner..

_+When I tested the below I had all "extra programs" closed. The only running programs where Terminal + top and Firefox.+_

*On battery*
- My CPU is @ 43-50 degrees (cel) in idle when on battery which is quite ok (CPU load under 5%)
- When I "stres" the CPU with some web browsing, the temp rises at once about 3-5 degrees. I have flash etc disabled in firefox. (CPU load 5% - 20% max)

*On AC*
- CPU load about the same but temperature is always some degrees higher.
- Top command shows the same processes as on battery.


When I open more programs, like Adium, Skype etc, the CPU load of course is somewhat higher (a few %) but CPU temp rises at once over 3 degrees which I think is ridiculous really.

Also it feels like the CPU never reaches the sleep state, is there a powertop like program for Mac´s?

http://www.lesswatts.org/projects/powertop/

Since you can not (yet) undervolt/underclock Core 2 Duo CPU´s like Centrino CPU´s (which was the best CPU Intel has ever made), how can I force the CPU to run at the lowest speed all the time (to 1Ghz which should be 500Mhz more than needed when you surf the web etc) and turn off devices that I do not need (USB ports, DVD drive etc etc)?

Also, is this Macbook 5.1 / Leopard with kernel 9.5.1 compatible with ULV CPU´s?

Any tips for increasing the battery life and make the laptop run cooler is much appreciated (ie, tips other than dimming monitor, turn of bluetooth etc). Ie, looking for how you can run wlan on less power etc if there is knowledge in Leopard for such things.

Thank You in advance for Your reply!

BR,
Chrisse

PS! I would have paid lots of more Euros for this machine with ULV CPU 😟

Macbook 5.1, Mac OS X (10.5.5), "Unibody"

Posted on Nov 30, 2008 4:28 AM

Reply
4 replies

Nov 30, 2008 5:35 AM in response to su_root

Some CPU info:

Core 2 Duo P7350 (the new Macbook 5.1 "unibody")
TDP = 25 W

Core 2 Duo SL9300 (the new Macbook Air)
TDP = 17 W

Core 2 Duo SU9300 (the processor I would like in my Macbook)
TDP = 10 W (!!!!)

SU9300 and SL9300 uses same socket on the motherboard. P7350 (which is a medium voltage CPU) uses different socket (socket P) and is thus not compatible with the low voltage / ultra low voltage CPU´s as in Macbook Air.

I guess the Macbook Air is not running much cooler due to the super slim design that makes it use smaller heatsinks for CPU? Does anyone know about this? If it runs cooler I consider selling this frying pan and choose a "real" laptop.

Or shall we all wait for a group of neards hacking the Intel Core 2 Duo family, allowing it to run on lower voltages? I really believe that the P7350 can be run stabile on 6x multiplier (instead of 7.5) and on 0.8 volts (instead of 1.0 volts which is minimum at the moment).

I undervolted my wifes ThinkPad T40 (Centrino CPU) and made it run on a much lower CPU multiplier. The result in battery life and heat was quite something (the CPU fan never runs anymore from a constant hair dryer before). There was no difference in speed when running light applications such as web browsing, chatting etc..

CPU´s, Intel and the heat just makes me sad.

Dec 1, 2008 7:46 AM in response to su_root

Regarding the heat problem, I've found a temporary solution. When I'm on AC I set the fan manually to about 3000RPM. Now I idle @ 34 degrees and it is no problem to sit with the computer in my lap anymore. The CPU fan obviously makes somewhat more sound now but it is still not that disturbingly loud. I will perhaps still open the case and apply quality thermal paste to the heat sink (it will probably get the temp down with 1-2 degrees at tops).

I still want to know:
- how to manually lock CPU speed to 1.0xGhz
- can I make the GPU run cooler (lowering the Mhz on RAM)?

-> or return to Linux?

Thanx in advance!

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CPU temperature in "Idle" when on battery / AC

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