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15" i5 over heating problems?

S

sarawr

macrumors member
Original poster
Sep 30, 2010
35
0
I am changing over to mac and had previously decided on a 13" but my town recently opened a leading edge that is a apple reseller so I was able to go in and see the macs for myself. After this I realised the 13" is far too small for doing any photo editing and graphic design with cs5 etc.

So I've decided on the 15" with i5 processor.

I read lots of reviews on it and a lot of people said they had over heating issues. The reason I'm changing to mac is because my current pc laptop has over heating issues and just is crap in general. I don't want to spend A$2200 on a laptop that is said to be reliable, but end up having to replace it or repair it down the line because of damage caused by over heating.

My question is, are the those complaining about a 70 - 90 degrees C over reacting or is it normal for the MBP to heat up this much? I won't be using it on my lap or in bed, it'll be on a desk where ever I go so I'm not worried about it being uncomfortably hot. My current pc runs around 50 degrees C during general use so I don't understand why 70+ would be so high for extensive use. If the MBP was over heating wouldn't it just switch it's self off, meaning if it's not doing this then it's not geting TOO hot, but just hotter than you expected?
 
Thanks :) Do you ever check the temps though? Give me an idea of a safe temperature for when I get mine. If it goes higher than what people think it should I'll get it replaced.
 
There might be some confusion between the CPU temperature and the case temperature (Apple calls it the enclosure temperature) in your reviews?

Apple designs its cooling system differently from most CPU manufacturers. The system tries not to dump heat into the enclosure and instead moves it from the CPU directly to the hinge using a heat pipe. From the heat pipe it gets dumped straight into the air. Whereas most PCs just dump the heat from the CPU into the interior of the enclosure, and then suck it out with fans.

Apple seems to make the most of this design by letting its CPUs get hotter than some PC laptops. But despite this, the enclosure does not get that hot. Each generation of MBPs has got better at having a hot CPU, but a cool enclosure. Sometimes you will read people bitching on here about getting a very hot enclosure, but that tends to be older models. The latest models have a fairly cool case. It can get a bit uncomfortable on bare legs, but is not going to burn you.

But this means all portable Macs have CPUs which can get up to >90 C under heavy load. Many (most?) go up to 105 C. This is within Intel tolerances, so I guess it's OK. It worries some people though (not me). If that is going to worry you, don't buy a Mac, or take steps using fan firmware hacks to solve the problem.

Intel designs the CPUs with multiple fail safes. At 105 C the CPU will lower its clock speed or even stop individual cores to reduce its heat dissipation and temperature. Your Mac would start to stutter and choke. At 125 C the CPU will completely shut down and so would your Mac.

I take the view that Apple has made millions (tens of millions?) of laptops with this >90 C CPU "feature". They have been doing it since the first Intel 'Books in 2005 or 2006. It doesn't seem to affect the reliability/longevity of Macs, or we'd have heard about it. Therefore IMHO it's probably OK. Also, Intel are the best in the business. If they say my CPU is good to 105 C, then I tend to believe them.

Finally when you read a review saying overheating, ask yourself what they mean...
1 - the CPU temperature exceeds Intel specifications for a significant time?
2 - the CPU gets so hot the machine shuts down?
3 - the CPU is hotter than comparable PC laptops?
4 - the enclosure gets too warm to touch?
5 - etc....

I guess they mean (3). IMHO who cares? Car magazines never discuss whether Toyota engines get hotter than Ford engines. As long as it goes 250,000 km who cares? That's definitely my point of view though, others I'm sure will come on here and flame me :)
 
sarawr said:
... If it goes higher than what people think it should I'll get it replaced.
Click to expand...

It doesn't really work like that. For a couple of reasons

1. All Macs are very similar. Swapping probably won't help.
Temperatures are remarkably consistent from Mac to Mac, if you run the same tests on them. The only possible differences are the CPU heat output, which varies a bit (perhaps 10%) from chip to chip, and the thermal paste, which despite what people say is very consistent from Mac to Mac. So swapping your Mac for another one is unlikely to solve the "problem". Because it's a design decision by Apple, not a fault with some Macs and not others

2. The fan control algorithm is designed to let your CPU get hot. The fan control firmware looks at the CPU temperature and decides what speed to set the fans at. The algorithm lets the CPU get to quite a high temperature (eg >80 C, depends on model) before it even starts to ramp up the fans. All Macs of the same model run the same fan control algorithm, ergo all Macs show similar CPU temperatures. (You can hack the fan control algorithm firmware to help a bit if you want)

3. In Apple's eyes it's not a defect, so they won't replace.
Apple doesn't think this is a defect, so why would they replace it? There is a thread somewhere on here called "My Mac reached 106 C" or something. He stress tested his CPU and it briefly got up to 106 C before settling down to a lower level. The guy tried to get a replacement. Apple said "No, your Mac is not faulty". I haven't read the thread recently, but the guy seemed to be having a hell of a time convincing them something was wrong.

Using the car analogy again:

Suppose you buy a shiny new Ford. Your friend buys a Toyota. You both download some software hack which allows you to see the engine interior temperature, say the exhaust valve temp. Your Ford's exhaust valves get 20 C hotter than those on your mate's Toyota. You go to Ford and say "hey, my exhaust valves are hotter than Toyota's. If those valves fail in 5 years, it's gonna cost me $$$$$$$. Gimme a replacement car.". Ford will just tell you to get stuffed:- it's not a defect; all Fords are the same; the temperature is within specifications; you're not really supposed to know about exhaust valve temperature.

With Macs you need to get used to the idea that a hot CPU is not a defect, it's a design choice. All Macs do it. Will it shorten the life of your Mac? No-one really knows, but the evidence seems to be that it does not, otherwise we would have big class action lawsuits, or lots of people on here bitching about premature logic board failure.

Ultimately it comes down to:- do you trust Apple's hardware engineers to design a quality, long-lived product? If not, don't buy a Mac.
 
Pax said:
But this means all portable Macs have CPUs which can get up to >90 C under heavy load. Many (most?) go up to 105 C. This is within Intel tolerances, so I guess it's OK. It worries some people though (not me). If that is going to worry you, don't buy a Mac, or take steps using fan firmware hacks to solve the problem.
Click to expand...
Thank you for explaining all that :D It was really helpful. It really doesn't bother me how hot it gets as longg as it doesn't damage anything in the computer. I just wanted an idea on average temps so I know what to expect or else I'd end up with a computer running at around 90 degrees and panic haha.
 
Pax said:
It doesn't really work like that. For a couple of reasons

1. All Macs are very similar. Swapping probably won't help.
Click to expand...

I didn't mean I would replace if it's hot, I meant if it was over heating more than apple or intel say it should, then I would ask for a replacement. It could sit at 100 degrees all day long if it wanted, and if intel and apple said its meant to I wouldn't be fussed about it. I'm not silly like some people that expect a laptop to be cold, I know they heat up :p
 
sarawr said:
I didn't mean I would replace if it's hot, I meant if it was over heating more than apple or intel say it should, then I would ask for a replacement. It could sit at 100 degrees all day long if it wanted, and if intel and apple said its meant to I wouldn't be fussed about it. I'm not silly like some people that expect a laptop to be cold, I know they heat up :p
Click to expand...

Cool! (Or not!). I don't think there is a real overheating problem with the i series Macs, it's just one magazine article which said they can reach 105 C, like all Macs made in the last 4 years.

Intel uses a threshold called Tj,max to define "too hot". If the CPU exceeds Tj,max it will take steps to protect itself, for example lowering clock speed or stopping cores. If the CPU exceeds Tj,max+25 C the processor will shut down completely. So it's completely fail safe.

For the i series processors, it's a tiny bit more complicated. The CPU package is really two chips in one package, a CPU and a graphics chip. The CPU has Tj,max of 105 C, the graphics chip of 100 C. Intel says "For power sharing designs it is recommended to establish the full cooling capability within 10°C of the Tj,max specifications. ... ".

Apple interprets this as:- the CPU temp can go up to Tj,max, but only for a few minutes. And then it should settle back down to Tj,max - 10 C. So that's maxing out at 105 or 100 C, and settling down at 95 C or 90 C for CPU and graphics respectively. Note that if the graphics part is generating more heat than the CPU part, the fans will pull the graphics part down to 90 C which might make the CPU temperature reading settle down to a quite low value. I think that's why different people report different CPU temperatures for their i series Macs - it depends what the two chips in the one package are doing.

If you are as dull as me you can read all about it here....
http://download.intel.com/design/processor/datashts/322812.pdf.
Table 18 and the text around it.

It's worth noting that these Core Macs are so fast, you will be hard put to find a workload that will really stretch them and heat them, apart from playing eg StarCraft 2, or running artificial benchmarks. For most normal tasks the CPU will spend time waiting on memory, disk etc and so won't often run "to the red line".

And if you have an overheating problem you will see it:- your Mac will stutter and/or shut down. If you monitor temperatures using a widget, don't be surprised to see your CPU reach 100 C or even 105 C for a couple of minutes, but it should gradually reduce to 90 or 95 C after a few minutes. Also don't be surprised that the fans take a loooonnnnnng time to ramp up. You will watch your CPU get hotter, and hotter, and hotter, and you will be convinced your fans are broken. But it's all normal!!

The only real overheating problems I've seen on these forums is with older Macs that have bad fans, fans full of fluff, or thermal paste that has aged and gone bad (mostly early Intel Macs). New Macs all seem very good in this regard.
 
Pax,
Thanks for your input. I assume the same is for iMacs. We just got an i7 2.93 quad and it gets really hot doing handbrake,sims3, etc.

We want a mbp and are looking at the 15 inch i5 and i7. Which in your opinion runs more hot?

Thanks
Michial
 
michial said:
Pax,
Thanks for your input. I assume the same is for iMacs. We just got an i7 2.93 quad and it gets really hot doing handbrake,sims3, etc.

We want a mbp and are looking at the 15 inch i5 and i7. Which in your opinion runs more hot?

Thanks
Michial
Click to expand...

I haven't looked at the iMac processors but I suspect the same temperature rules apply.

I don't know for sure whether the MBP i5 or the i7 will be hotter. But they both have the same power output and so should in principle generate the same amount of heat, and they both have the same Tj,max temperature. So I doubt there will be any practical difference between the two. For this reason I personally would not let temperature worries affect my decision between an i5 and an i7.

Remember Apple designs all its laptop CPUs to run hot. It's not a bug, it's a feature (thinner laptop, metal case, quieter fans). More or less all its laptops over the last 5 years let their CPUs get to the same temperature (Tj,max for a few minutes, then Tj,max - 10 C for the long term). So it's a good bet that an i5 and an i7 MBP will get equally hot equally quickly.
 
Macs have always been hot computers probably because of their thin case designs. My Macbook Pro just went up to 90 degrees celsius in Maya today. The fans didn't even go up that much. I sped up the fans with SMC fan control (thank goodness for that app) to prevent overheating.
 
Pax said:
I haven't looked at the iMac processors but I suspect the same temperature rules apply.
Click to expand...

i dont really see heat as an issue for apple computers - unless something is physically wrong with the computer. i believe apple controls the fans/heat very nicely :)

my iMac idles at 54°C. under load it wont go above 65°C once the fans kick in. this is FAR below TjMax

in the case of the MBP, its a similar scenario - WELL below TjMax :)

ive yet to see any temperature results from the OP as of yet, but i suspect everything is ok.
 
CHill your Macbook

Listen... I got a macbook pro mid 2010 i7 and it gets hot, especially when playing video or other CPU/GPU 'taxing' activities. What I do is use a 8x10 frozen gelpack under the mac and I get temperatures of under 40 deg Celsius with fans at 2000 rpm compared to 70-80 without and One gelpack is good for this for over 3 hours. So go buy a few gelpacks and enjoy a cool mac, Then just throw it back in the freezer. The type i use are from a company called Cryopak. Works for me. If you don't don't want to use the gelpack method just get smc fan controll and run your fans at full tilt and burn your legs off.
 
JonnyMac1971 said:
Listen... I got a macbook pro mid 2010 i7 and it gets hot, especially when playing video or other CPU/GPU 'taxing' activities. What I do is use a 8x10 frozen gelpack under the mac and I get temperatures of under 40 deg Celsius with fans at 2000 rpm compared to 70-80 without and One gelpack is good for this for over 3 hours. So go buy a few gelpacks and enjoy a cool mac, Then just throw it back in the freezer. The type i use are from a company called Cryopak. Works for me. If you don't don't want to use the gelpack method just get smc fan controll and run your fans at full tilt and burn your legs off.
Click to expand...

HAHA i have never heard of that! just please ensure that you dont get any moisture inside the laptop!
 
michial said:
Macworld 2010 expo had these guys selling these pads at a booth. I may pick one up.

http://www.amazon.com/ThermaPAK-HeatShift-Laptop-Cooler-Black/dp/B001CBFTFM
Click to expand...

i laughed at this:
• "Uses no power so laptops last longer"

i thought it was cooled, not self cooling - not that keen on it in that instance.

AdamRock said:
theres so much mixed reviews, some people said it workers other said it went hotter...
Click to expand...
had a quick look, they are quite mixed. i wonder what substance is inside it.
 
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