Runs hot under Win 7 - Normal?

That's Windows for you.

BasilFawlty said:

I'm new to iMac - just got a 27" i5 a few months ago, after years on a Dell PC. Anyway, I installed Win 7 under Bootcamp and it works fine; however, I notice that the computer body seems much hotter when I run Windows 7 than when I'm running MAC OS. Is this normal, or is there something I need to do on the Windows side to improve cooling?

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Since Lion 10.7.2 the Lion side runs a bit cooler than the windows side. Two things you can do: get something like MacFan0_6 and make a *.bat file that you use to set the inimum speed. You can also go into control panel, power options and set the minimum CPU speed from 5% to 3%. You can also set there to go to passive cooling but it all depends on how hard you are driving the machine.

blueroom said:

That's Windows for you.

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No, that's Apple's drivers for Windows for you.

MJL said:

Since Lion 10.7.2 the Lion side runs a bit cooler than the windows side. Two things you can do: get something like MacFan0_6 and make a *.bat file that you use to set the inimum speed. You can also go into control panel, power options and set the minimum CPU speed from 5% to 3%. You can also set there to go to passive cooling but it all depends on how hard you are driving the machine.

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Thanks didn't know you could change minimum processor %.

What is the difference between passive and active cooling?

auhlixer said:

Thanks didn't know you could change minimum processor %.

What is the difference between passive and active cooling?

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Active cooling depends on the fan coming on when the CPU gets hot, passive cooling throttles the CPU back before using the fan. If you are doing mainly browsing, writing documents you'll use the latter, when doing CPU intensive stuff you'll use the former.

blueroom said:

That's Windows for you.

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That's trolling for you.


I have seen these things run a bit hotter in Windows. I somehow doubt Apple spends much time worrying about how they run Windows as it's more of a feature than intended design for these machines. Unfortunately Macs don't have as many nice up to date fan control programs for Windows as they do under OSX.

Also it might run a little cooler if you disable Aero. That trick definitely works on laptops with integrated graphics. I'm not sure if it would do much for the imac. Windows overall when it's not updating has a very low cpu overhead when you aren't doing anything. If not much is really running you may see around 97% assigned to system idle process.

Setting Power Options > Minimum CPU to 5% and Power Options > Link Power Management to Moderate Power Savings considerably drops the temperature. Also, if you are using AHCI you already know that Sleep (S3) does not work, but you can still turn off the drives in Power Options > Hard Drive > 20 Minutes. Also, if you are not pushing the processor or even if you are gaming with a discrete card you may want to try setting Power Options > Maximum CPU to 99%. This supposedly turns off Intel Speed Step and prevents over clocking which equals less heat.

windows does this alot of time. I have the same problem

blueroom said:

That's Windows for you.

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I just built a Windows 7 PC that idles at about 25C, and when stressed using Intel Burn Test burn-in software, the processor runs at a maximum of 50C. Just because your iMac runs hot, that makes win 7 bad? Give me a break!

It's normal, either Apple does some magical hardware specific coding under OS X, or their drivers for Windows are terrible.

No kidding, it's running VERY hot with Windows 7. A 2010 iMac.

It has nothing to do with windows 7, it's all due to the drivers and the way apple won't allow hardware to go into sleep/idle mode under windows, which means your graphics card for instance runs at full power all the time, even when you do nothing, which is mostly fine, but it creates a lot of heat.

I did a test a while ago when I redid my Windows partition and I used Hardware Monitor to see the temps before I had installed the Boot Camp drivers. The tests were wow! IT seems before I installed the drivers that the temps were as cool as on the mac side but as soon as I installed the Boot Camp drivers that is when the temps started going higher.