Welcome to the MacNN Forums.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Notebooks > My MacBook throttles its CPU under full load -- does yours?

View Poll Results: Does your MacBook throttle under full load?
Poll Options:
Yes, my MacBook is an underachiever 5 votes (38.46%)
No, I'm a lucky punk 8 votes (61.54%)
Voters: 13. You may not vote on this poll
My MacBook throttles its CPU under full load -- does yours?
Thread Tools
Kyon
Fresh-Faced Recruit
Join Date: Jun 2006
Status: Offline
Reply With Quote
Jun 20, 2006, 02:06 PM
 
I bought a 2.0 GHz (white) MacBook just over two weeks ago. (It was built on week 21, for those of you keeping track of serial numbers.) In general I love it -- it doesn't even get that hot; the hottest I've seen it (per CoreDuoTemp) is 80 degrees C, which isn't anywhere near as bad as some others' temperatures.

The only problem is that my computer can't/won't run at 2.0 GHz under full load for any sustained length of time. In fact, the only time I see it perform at full speed is when I begin using it after it has been off/asleep for several hours beforehand -- and even then it only does so for a few minutes.

I've been surprised by the lack of discussion about this issue; I don't think it affects every MacBook made, but I suspect that it might affect more MacBooks than people realize. So, if you own a MacBook, could you run a test for me?
----------
0) Set your energy saver preference to "maximize performance," and plug in your MacBook. Don't give it any excuses not to perform.

1) Download CoreDuoTemp (if you haven't already), and open it up. In its preferences, tell it to update every one or two seconds. You'll be paying attention to the "current frequency" value that CoreDuoTemp reports.

NOTE: MacBooks throttle their processor to 1.5 GHz when they aren't being taxed, as a way to conserve battery life. Don't worry about that, until you actually do something with your machine.

2) Quit all other open programs, and do one of the following things to put your machine at 100% load:
a) Copy the Chess application twice, and open all three copies. Start a new game in each, having the computer play against itself.
b) Run "yes > /dev/null" in each of two Terminal windows (one for each processor)
c) Run "openssl speed" in each of two Terminal windows (one for each processor)

[Note: if you choose to run Terminal commands, you can end them, later, by pressing control-z]

3) Watch what CoreDuoTemp tells you as time passes (this should be no more than 5-10 minutes). Your temperature should rise, and your current frequency should rise and remain at your computer's rated speed (e.g. 2000 MHz for a 2.0 GHz machine). If it doesn't do that -- if your computer's current frequency perpetually stays lower than its rated speed (or perpetually drops temporarily below its rated speed), once the temperature has risen... you have an underperforming MacBook.
----------
This, at least personally, does have a real-world effect on the speed of the machine. I've run CineBench on my MacBook under a variety of conditions. In CineBench, a 2.0 GHz Core Duo chip running at full speed seems to report a single-CPU score of 305 (+/- 5) and a dual-CPU score of 575 (+/- 5). My MacBook only gets those scores when I run CineBench immediately after leaving my computer off for several hours; if I've been using the computer for a while and then restart and run CineBench, I can get CineBench single-processor scores as low as 276 (though, usually, my single-processor score is about 305), and dual-processor scores as low as 412 (though I generally see a score here of 530 -- which still isn't that good).

I, of course, have called AppleCare about this. [FYI, their official stance is that they can't do anything based off of what third-party applications say. While understandable, Apple doesn't actually provide a first-party CPU frequency monitor or benchmark program -- which makes it a tough case to argue.]

The specialist was able to reproduce the throttling on his MacBook, and conferred with his engineers; their consensus was that this is normal, and that every MacBook should do this. He says there have been no revisions to the MacBook so far -- ostensibly, then, every MacBook should be the same (barring one-off issues). I've heard reports of MacBooks that are capable of running at full speed under load, however...
     
StevenWRX
Forum Regular
Join Date: Oct 2003
Location: Houston, TX
Status: Offline
Reply With Quote
Jun 20, 2006, 04:11 PM
 
i think this is a good point to bring up. it'll be interesting to see what everyone says.

( i cant test my macbook since i returned it.. i gave up on rev. A )
-Rev. C PowerBook 17" 1.5GHz
-iPod Mini 4gb Silver (Rev. B)
-Gaming Rig: AMD Athlon 64 X2 4200+ Manchester, Asus A8N-E, 2 Gig Corsair XMS, nVidia GeForce 7900GT PCI-E, Seagate 320gb Barracuda HDD, Samsung 16X Dual Layer w/ LightScribe, Thermaltake Tsunami, Antec 550W True Power 2.0, Saitek Eclipse Keyboard, Logitech MX518 Gaming Mouse, Samsung 19" 931B.
     
harrisjamieh
Mac Elite
Join Date: Jun 2005
Location: UK
Status: Offline
Reply With Quote
Jun 20, 2006, 04:48 PM
 
According to Apple's site (I forget where..), the CPU will throttle to help keep bearable temperatures, making sure the MacBook does not overheat. The reason this throttling happens more at higher loads is that more heat is generated during heavy load, hence the CPU will further throttle to reduce heat
iMac Core Duo 1.83 Ghz | 1.25GB RAM | 160HD, MacBook Core Duo 1.83 Ghz | 13.3" | 60HD | 1.0GB RAM
     
Socially Awkward Solo
Professional Poster
Join Date: Jul 2002
Location: Hanging on the wall at Jabba's Palace
Status: Offline
Reply With Quote
Jun 20, 2006, 05:02 PM
 
Originally Posted by harrisjamieh
According to Apple's site (I forget where..), the CPU will throttle to help keep bearable temperatures, making sure the MacBook does not overheat. The reason this throttling happens more at higher loads is that more heat is generated during heavy load, hence the CPU will further throttle to reduce heat
That is kinda chicken and the egg then isn't it.

"Laugh it up, fuzz ball!"
     
darth-vader000
Forum Regular
Join Date: Jun 2006
Status: Offline
Reply With Quote
Jun 20, 2006, 06:07 PM
 
I said before, I wish apple provided a way for us to control the cpu speed and the fans. I think I know when I need the cpu to be set at the highest setting. Heck the powerbooks and G5s had the ability to set the processor performance to highest, automatic, reduced. Add on top of that the ability to turn the fans on or off.
     
PBG4 User
Senior User
Join Date: Feb 2001
Location: Deer Crossing, CT
Status: Offline
Reply With Quote
Jun 20, 2006, 07:35 PM
 
I have my 1.83GHz MacBook (bought yesterday) set to normal performance. Doing the yes > /dev/null in two Terminal windows brings my CPU usage to 100% and my CPU frequency to 1.83GHZ, according to Core Duo Temp. My temperature topped off at 83C after running for about 5 minutes. My serial starts with 4H623.
20" iMac G5! :D AND MacBook 1.83GHz!
Canon Digital Rebel Kit + 75 - 300mm lens. Yum Yum! :D
Check out my OS X Musical Scales program
     
frdmfghtr
Senior User
Join Date: Nov 2005
Status: Offline
Reply With Quote
Jun 20, 2006, 08:20 PM
 
80 degrees C = 176 degrees Fahrenheit...why does that sound WAAAAAAY too hot to me?

What's the specification for the Core Duo? I'm looking at the Intel site and sa far I haven't found it.

[Update]

OK I found a sample spec...the Intel® Core™ Duo processor T2300E (1.66 GHz) is rated to 100 C. So I guess you can cook eggs with it That just sounds so blooming hot though.
( Last edited by frdmfghtr; Jun 20, 2006 at 08:27 PM. )
     
StevenWRX
Forum Regular
Join Date: Oct 2003
Location: Houston, TX
Status: Offline
Reply With Quote
Jun 20, 2006, 10:12 PM
 
Originally Posted by harrisjamieh
According to Apple's site (I forget where..), the CPU will throttle to help keep bearable temperatures, making sure the MacBook does not overheat. The reason this throttling happens more at higher loads is that more heat is generated during heavy load, hence the CPU will further throttle to reduce heat

so that means people are paying for a dual 2.0 ghz machine, yet it will never run at that speed because it gets too hot..?

so when you NEED all the processing speed, it wont achieve it because it will "throttle" itself down to prevent overheating.. AND when you dont need full performance, it still "throttles" down to preserve battery life?

I believe it since it makes sense. BUT that means owners of 2.0 macbook will never get full 2.0 ghz performace.

Now i am really glad i returned my macbook 2.0
-Rev. C PowerBook 17" 1.5GHz
-iPod Mini 4gb Silver (Rev. B)
-Gaming Rig: AMD Athlon 64 X2 4200+ Manchester, Asus A8N-E, 2 Gig Corsair XMS, nVidia GeForce 7900GT PCI-E, Seagate 320gb Barracuda HDD, Samsung 16X Dual Layer w/ LightScribe, Thermaltake Tsunami, Antec 550W True Power 2.0, Saitek Eclipse Keyboard, Logitech MX518 Gaming Mouse, Samsung 19" 931B.
     
Juba310
Fresh-Faced Recruit
Join Date: Jun 2006
Status: Offline
Reply With Quote
Jun 21, 2006, 12:12 AM
 
I just ran the yes >dev thing, and it brought me up to 2.0 ghz solid. Temp rose to 171°F before I made it stop.
     
greenamp
Mac Elite
Join Date: Jun 2004
Location: Nashville
Status: Offline
Reply With Quote
Jun 21, 2006, 12:39 AM
 
Ran two yes > /dev/null terminals for 5 minutes.

My BlackBook gets to about 85c before the fans kick in (noticeably) and keep it right at 80ish. My CPU speed remained a solid 2000mhz for the entire 5 minutes of 100% load.

After closing both terminals, within 10 seconds temp dropped to about 55c, and clock speed back down to 1500mhz. Fan kicked off or was no longer audible at 70c. Mine seems fine.
( Last edited by greenamp; Jun 21, 2006 at 12:48 AM. )
     
hatim
Forum Regular
Join Date: Jun 2006
Status: Offline
Reply With Quote
Jun 21, 2006, 08:09 AM
 
Mine gets to 85-90 after 30 mins at full load depending on the ambient temps. Why should I be worried when I have 340 days more of warranty left?
     
darth-vader000
Forum Regular
Join Date: Jun 2006
Status: Offline
Reply With Quote
Jun 21, 2006, 10:35 AM
 
Originally Posted by hatim
Mine gets to 85-90 after 30 mins at full load depending on the ambient temps. Why should I be worried when I have 340 days more of warranty left?
Because, one night, your working late trying to finish a presentation for tomorrow's meeting, and boom, a component fails because it was subjected to excessively high temperatures.

Will your MB be covered, yup,
Will you have to be without the MB for a period of time, yup
Will it effect your ability work - maybe.

I spent a lot of money on the computer and I'm pretty happy with the MB, but Apple's non-answer that it runs hot doesn't really alae my fears that I may incur trouble down the road. I use my MB quite a lot and I really cannot live w/o it - even if its covered by the warranty.
     
   
Thread Tools
 
Forum Links
Forum Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Top
Privacy Policy
All times are GMT -4. The time now is 03:25 AM.
All contents of these forums © 1995-2017 MacNN. All rights reserved.
Branding + Design: www.gesamtbild.com
vBulletin v.3.8.8 © 2000-2017, Jelsoft Enterprises Ltd.,