Most "hot" 2011 MacBook Pros are not actually "overheating".
There have been lots of discussion and rumors lately about the 2011 MBPs overheating. People hear about "excessive thermal paste" and assume that's the reason their computer seems hot. I've googled this. A number of
individuals have reported that replacing their thermal paste with arctic silver and getting 10-degree reduction in temperature. Unfortunately, they don't always report whether that's in degrees C or F. On the other hand, a few
professionals have investigated this issue and found much less significant improvements. The 2006 MBPs were purportedly the worst, yet changing the thermal paste didn't help much, and the latest models have lower TDP and better cooling.
Although Apple might possibly be able to use a marginally better thermal paste, this issue of it being "excessive" is probably a red herring. The heat sinks are pressed against the components with a huge amount of force. It doesn't matter how thinly or thickly you apply it -- nearly all of it is going to squish out from between the processor and the heat sink. The only possible problems would be if the excess were to get onto other components, interfering with their airflow, or over a period of years if the excess paste were to migrate around the machine and get into a place where it causes problems. As far as I have been able to determine, neither has been reported to happen.
One common reason for an apparently idle system to get hot is that it is not in fact idle. Spotlight indexing is a resource hog that uses significant CPU time. In fact, a number of users have reported that their brand new MBP was overly hot until they let spotlight run its course, which took a really long time, and then it was cool as a cucumber. Not everyone thinks to check to see what their computer is doing.
For those of you who feel that your Mac is overly hot when idle, wait until you find that the computer is hot, and open the "Activity Monitor" app. In the lower portion of the window, select the CPU tab, and in the upper right, be sure "All Processes" is selected. Watch it for a bit. Your computer may not actually be idle. (BTW, iStat misreports process names, so use Activity Monitor instead.) You've not personally commanded it to do anything compute-intensive, but MacOS X runs a lot of background processes like Time Machine and Spotlight that will run up your CPU temperature. This is completely normal.
For those of you who are finding the machine to be excessively hot +under heavy load+, you need to check your actual CPU temperature. I can't find the specs on the current Sandy Bridge, but in general maximum junction temperatures for Intel CPUs have ranged primarily from 90C to 100C. Use a tool like iStat to check your CPU temperature. If it's below 90C, then you're safe. The case may be hot, bur your computer is okay. If it increases above 90C, then I'd start to get nervous.
From personal experience, I can tell you that I damaged my 2007 MBP by running the CPUs at max for a protracted period. At the time, my MBP was the fastest computer I could get access to, and I was running vector-heavy code on both CPUs. For two weeks straight, the CPUs were at 90C. What I didn't realize was the CPU fans were not spinning at max RPM. If I had used one of the fan control utilities to fix that, damage might not have occurred. As it was, I later started getting kernel panics and such, which were solved by replacing the main memory sticks.
Since that time, the internal structure of the MBPs has changed so that the DRAM probably gets better airflow. But if you're going to do a lot of compute-intensive stuff, then here are three potentially useful pieces of advice:
(1) Install a fan control utility. Most tools let you set minimum fan speed. I prefer Lobotomo's Fan Control, which gives you more flexibility.
(2) Buy AppleCare. In theory, running the CPUs hot like that is within the design specs of the machine, but really, we're talking about notebooks here that prioritize portability over many other factors. Running them hot for long periods is pushing their limits, which has the potential to cause damage. Apple has a wonderful extended warranty. Use it.
(3) Consider using a desktop or server machine instead. Those have the luxury of having better internal airflow. They're designed for compute-intensive applications. Running 3D games on my old MBP makes it really hot, and the fans get loud. Running the same things on my iMac makes it slightly warm, and I can barely hear the fans.
Let me remind you that Apple is careful to describe these machines as "notebooks", not "laptops". As an engineer who has designed computer systems at various levels, I can tell you that price, performance, and convenience (e.g. weight and size) are a fine balancing act. If Apple were to design these machines to be a lot cooler, they would likely have to make them much more expensive, much less capable, or larger. Indeed, people posting in these forums are generally reporting the larger models (15" and 17") to be cooler than the 13". And you'll notice that the MacBook Air had to be significantly scaled back in performance to fit in that small enclosure without getting hot.
As a final word, although I think that Apple's quality control is better than the rumor mills would have you believe, there are going to be a small number of defective machines. If you've tried everything, and your computer is still too hot, then take it back to the Apple Store and politely ask for a repair or replacement. Apple Store employees are there to make Apple revenue, and the best way to do that is to keep the customers happy so that you'll by another Mac later, and your friends will buy Macs, and so forth.
Although Apple might possibly be able to use a marginally better thermal paste, this issue of it being "excessive" is probably a red herring. The heat sinks are pressed against the components with a huge amount of force. It doesn't matter how thinly or thickly you apply it -- nearly all of it is going to squish out from between the processor and the heat sink. The only possible problems would be if the excess were to get onto other components, interfering with their airflow, or over a period of years if the excess paste were to migrate around the machine and get into a place where it causes problems. As far as I have been able to determine, neither has been reported to happen.
One common reason for an apparently idle system to get hot is that it is not in fact idle. Spotlight indexing is a resource hog that uses significant CPU time. In fact, a number of users have reported that their brand new MBP was overly hot until they let spotlight run its course, which took a really long time, and then it was cool as a cucumber. Not everyone thinks to check to see what their computer is doing.
For those of you who feel that your Mac is overly hot when idle, wait until you find that the computer is hot, and open the "Activity Monitor" app. In the lower portion of the window, select the CPU tab, and in the upper right, be sure "All Processes" is selected. Watch it for a bit. Your computer may not actually be idle. (BTW, iStat misreports process names, so use Activity Monitor instead.) You've not personally commanded it to do anything compute-intensive, but MacOS X runs a lot of background processes like Time Machine and Spotlight that will run up your CPU temperature. This is completely normal.
For those of you who are finding the machine to be excessively hot +under heavy load+, you need to check your actual CPU temperature. I can't find the specs on the current Sandy Bridge, but in general maximum junction temperatures for Intel CPUs have ranged primarily from 90C to 100C. Use a tool like iStat to check your CPU temperature. If it's below 90C, then you're safe. The case may be hot, bur your computer is okay. If it increases above 90C, then I'd start to get nervous.
From personal experience, I can tell you that I damaged my 2007 MBP by running the CPUs at max for a protracted period. At the time, my MBP was the fastest computer I could get access to, and I was running vector-heavy code on both CPUs. For two weeks straight, the CPUs were at 90C. What I didn't realize was the CPU fans were not spinning at max RPM. If I had used one of the fan control utilities to fix that, damage might not have occurred. As it was, I later started getting kernel panics and such, which were solved by replacing the main memory sticks.
Since that time, the internal structure of the MBPs has changed so that the DRAM probably gets better airflow. But if you're going to do a lot of compute-intensive stuff, then here are three potentially useful pieces of advice:
(1) Install a fan control utility. Most tools let you set minimum fan speed. I prefer Lobotomo's Fan Control, which gives you more flexibility.
(2) Buy AppleCare. In theory, running the CPUs hot like that is within the design specs of the machine, but really, we're talking about notebooks here that prioritize portability over many other factors. Running them hot for long periods is pushing their limits, which has the potential to cause damage. Apple has a wonderful extended warranty. Use it.
(3) Consider using a desktop or server machine instead. Those have the luxury of having better internal airflow. They're designed for compute-intensive applications. Running 3D games on my old MBP makes it really hot, and the fans get loud. Running the same things on my iMac makes it slightly warm, and I can barely hear the fans.
Let me remind you that Apple is careful to describe these machines as "notebooks", not "laptops". As an engineer who has designed computer systems at various levels, I can tell you that price, performance, and convenience (e.g. weight and size) are a fine balancing act. If Apple were to design these machines to be a lot cooler, they would likely have to make them much more expensive, much less capable, or larger. Indeed, people posting in these forums are generally reporting the larger models (15" and 17") to be cooler than the 13". And you'll notice that the MacBook Air had to be significantly scaled back in performance to fit in that small enclosure without getting hot.
As a final word, although I think that Apple's quality control is better than the rumor mills would have you believe, there are going to be a small number of defective machines. If you've tried everything, and your computer is still too hot, then take it back to the Apple Store and politely ask for a repair or replacement. Apple Store employees are there to make Apple revenue, and the best way to do that is to keep the customers happy so that you'll by another Mac later, and your friends will buy Macs, and so forth.
Mac OS X (10.6.2)