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Sossity

macrumors 65816
Original poster
May 12, 2010
1,360
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I use a windows program to encode my albums in flac format to mp3, using windows xp pro with paralells desktop 5.0.

I have noticed a difference when doing this from my external hard drive connected via firewire 800 to my macbook pro. The encoding speeds are twice as fast, but during it, I can hear the fans kick in on my macbook pro, I looked in istat pro, & the cpu went up as well as the fan speeds, cpu was at about 143 & the fans at about 3000 I dont remember the exact speed.

The external hard drive has a hitiachi deskstar 7200rpm 1TB hard drive in it with 32mb cache, in a macally enclosure.

Is this normal? or will I risk burning out my laptop? I thought firewire 800 did not use the computer's cpu?

I may do a comparison & do this all with hard drive connected via usb 2.0. I do remember when I used usb before, that the encoding was slower, but I did not check fans or temperature. With usb 2.0, I dont remember hearing the fans as I do now.

would it be safer for my laptop to use usb 2.0? even if it is slower?
 
It's perfectly normal for your temps and fan speed to increase when doing any CPU/GPU intensive activities. There's nothing to worry about. If temps get too high, your Mac will simply shut down. Many have run with temps as high as 105C and fan speed over 6,000 rpm without shutting down.
 
Is this normal? or will I risk burning out my laptop? I thought firewire 800 did not use the computer's cpu?
correct, firewire is much faster than usb, and firewire operates in DMA mode, bypassing the host CPU. Because it's a fast interface, it is able to feed your audio transcoding job much faster than usb would. and audio transcoding is very CPU intensive. so the reason your fans kick in, is that you are doing more work in less time!! it's a good thing!!

there is no risk of burning up anything- the fan speeds are controlled by OSX, and even if they failed, the CPU has thermal protection at the hardware level and will shut itself down if it gets too hot.
 
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