I'm not sure where you got those numbers from, but they're not correct. 50C is perfectly fine. If under heavy load, the CPU can easily get up over 90C and that's fine, too. The computer will shut down if it overheats, but that won't kick in until about 100C.
Assuming it does kick in. There were reports of 2010 MBPs that got to 105C and they didn't shut down... maybe they lacked the power function override...
It's the same Intel CPU found in any ol' laptop, and they don't always shut down... There was a (Sandy Bridge-based) Dell that got fried despite the assurance of "it will shut down on its own, the temp is A-OK, etc").
Even if it does, since the fans will shut down right along with it, and with the pesky laws of physics prevailing, the level of heat pent up will still likely damage the CPU -- or reduce its lifespan.
Just because a CPU can run at x degrees C does not mean it
should.
A GOOD design prevents temps from getting that hot in the first place. It's that simple.
Mine idles at 35C in a room that's around 20C. When under full load, it gets into the 90s. It typically hovers in the 40s, but gets into the low-60s during app installs or during Photoshop use (typically high-50s). All of those are great temps.
I will not render, or do anything that gets the CPU over 85C. Not for more than 15 minutes or so, and I use SMCFanControl to up the fans to full.
Especially with smaller CPUs using smaller electricity paths (22nm, etc), electromigration can become an issue and heat worsens the potential for premature failure. Any Sandy Bridge overclocking forum will go more into detail, but both heat and overvolting (the latter can't be done on Macs, thankfully) are both very legitimate concerns.
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It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.
I have to disagree with that.
Even googling "aluminum vs plastic insulator" will reveal the same things: Aluminum is, by far, the better
insulator - meaning it's trapping air and keeping the innards hotter. Plastic is porous (and leeches chemicals into liquids, which is why I don't care for plastic drink containers, but I digress). Being porous means the thing can 'breathe' - hot air escapes more effectively than the (near-nonexistent) air channel inside the MBP's chassis (the 2012 rMBP purportedly rectifies this, but I've yet to use one... would love to buy one since I've practical uses for it too, but not for a while...)
I had a 2010 Sony quad core laptop that never got above 76C. It was plastic junk. The finely designed aluminum 2009 MBP got to 98C when compiling code. Aluminum transfers heat only when in direct contact. These things are not gigantic heatsinks, otherwise we wouldn't see news article after news article of high temperature problems.
Even users replacing the gobs of (clearly low-quality) thermal grease with proper quantities of good grease (e.g. Arctic Silver, or others) have seen a
10C drop (my2011macbookpro.com, ifixit).
These things are not ideally designed based on temperatures under load, and plenty of articles are very telling in that they are not well made. Not for the prices being commanded.
But that is a myth, which I used to believe when I first bought mine and until I saw the temperatures speak for themselves, that aluminum channels out hot air. It doesn't. It is not a heatsink, for it is not attached to the heat-generating elements (CPU, GPU, northbridge, etc). It therefore acts as an insulator.
Physics and reality - I hate them too.