MacBook Pro duty cycle - can it be run at full CPU for extended time?

Question

Hello,
I'm wondering if anyone knows Apple's stance on the duty-cycle of the MacBook Pro models. I'm should be receiving a MBP Core2Duo 2.16 GHz in a couple days.
The reason I ask is that I currently have a PowerBook 1.33 GHz, and do a good deal of rendering of 3D computer graphics. On my PowerBook, when it is running under full load, the fan will come on for a while.. then turn off... then on for a while etc. It doesn't seem to have problems keeping the temp down unless the ambient temp of the room is high (say, above 80 F, 26C, which then is my fault and I need AC... lol, not computer design).
I have had a few MacBook Pro units from work, and they work quite differently. The fan always runs... usually around 1k RPM, and then spools up to compensate for load. I have had two left fans go bad in 1.83 GHz Duo Core units (fairly early in production), and recently got a 2.33 GHz at work. I put it under full load tonight for a while, and the fans spun up to about 4k RPM (they seem to idle at 2k RPM). This kept the temp of the CPU to around 79 C... which is a bit higher than I like... but probably safe (and our room temp is fairly cool this time of year... about 70 F, 21 C).
I'm wondering if it is safe to run a MBP like this for extended periods of time. I'm talking days here, 24x7... not just an hour or two. I have done this MANY times on my PowerBook G4 1.33... and it is probably like 3 years old or so now. Having those fans go out has just made me a bit gun shy I guess. Should I expect to be able to do this kind of thing with a 'Pro' laptop... or am I just running them too hard? Or, were there just a bad run of fans in the earlier MBPs?... it was always the left fan.
-Steve

Answer 1

Actually, I don't think 4,000 RPM is all that great,
and the fans shouldn't have any trouble maintaining
this speed indefinitely. 10k or more would be a
different story.
Of course, this is true only if the fans are designed
(and built) properly. I can't speak to that.
Yea, that's what I'm afraid of (fans not designed for that). It might be because I've actually witnessed a couple go bad... but I just don't think most of these tiny PC type fans can take it. Graphic card fans are notorious for going bad too. I'm less concerned with keeping the CPU temp down than I am with the high RPM on the fans actually.
Regardless, you should be able to run your MBP "full
bore" for as long as you like, and you needn't worry
about it failing.
I think you're correct... other than the fans. I'm guessing they will fail. If they did, the computer would probably just shut down. It probably wouldn't hurt anything, just need the fan replaced. But, I'd rather avoid that if I can. I suppose I could replace it myself to keep from having to send it away for a week or two.
There is one thing, however, that
most people do not consider, and which will help more
than anything else (maybe even room temp): Keep the
air around your MBP moving!
Bingo! Great lead. I guess I knew this but didn't think of how big of difference it really would make. So, I did some experimenting.
I brought up my trusty iStat Nano Dashboard widget so I could see the fan speed. Then I took a folder and fanned the computer for a couple minutes. Just this amount of air movement dropped the RPM from around 4600 (for some odd reason, my 2.16 runs at higher RPM than my 2.33, and keeps the CPU a couple degrees cooler) down to 2800. WOW!
Then my arm got tired, and I went to get a rather powerful fan I could fit on my desk (one of Honeywell vortex type fans), and then it dropped to 2200 RPM. This fan is WAY to noisy, but my folder experiment demonstrated I don't need all that much air movement... just like you said.
I think I'm going to go tomorrow and get either a couple of small fans, or maybe even some low noise computer fans and experiment with some ways of mounting them. I should be able to keep it down in the mid-2500 RPM range and still be quiet if I get the right setup.
Also, I think you can safely disregard what your
"overclocking" friends have to say. True, 100 C is
quite hot, and would certainly be too hot for earlier
processors. The Core Duo, however, is an entirely
different beast, and Intel has designed it to run
that hot. I think your friends are probably
(inappropriately) applying specs for earlier
processors to the Core Duo.
I checked the Intel specs on the Core2Duo, and it has an operating max of 100 C. It some kind of actual hardware failure type shutdown at 120 C. So, I guess 80 C is hot, but 20 C under the max operating temp. I'm sure Apple designed it to keep that temp safe, so I guess they just vary the fans to keep it under 80 C the way it looks.
Thanks much... that tip will solve my issue!
-Steve