iMac running very hot

Kutten1303 wrote:

I quit Safari, but still the same. Just spoke to Apple guy and we worked through the machine, with Activity Monitor to see whats going on in the Mac and so on. But still no solution.

How about trying that again? Set it to show "All Processes", sort by "CPU", and take a screenshot and post here.

Baltwo wrote: When the original was replace under the iMac HD replacement program, the techs were satisfied that the temp was OK. Still have 11°C to go, since the temp sensor is on the drive case.

The OP's drive is exactly the same as mine, a WD rated to 55C. Although my WD is rated for 55C, I would never run it that hot. My car engine may be rated to a certain number of rpms, but constantly redlining it won't be too healthy for it. And, btw, isn't the temp sensor internal on your 2011, not an external stuck on to the case? It is internal on mine, which is a late 2009. Your temp sensor readout is likely to be internal, not case.

And, obviously, since the OP's power supply is way too hot at 75C, with or without only Safari open, something else is going on that needs to be explained.

I'm also hearing many new to ML from other OSs who are saying that ML raises the temps considerably.

For smcFanControl, try running the fans not quite so fast, maybe around +600 rpms. You shouldn't hear them at that speed. To do that, set a new favorite.

As mentioned previously, running a fan at the back can help considerably. And, can you post a screenshot from Activity Monitor when the computer is running hot? Might need two screenshots to cover all processes. Have you vacuumed out the fan intake grilles? Might also help to remove the RAM door and put the vacuum there. But avoid touching anything inside with the vacuum attachment.

If your room temp is around 91+, that's just too hot and you'll only be blowing hot air around, to no great benefit.

Not sure about the fan behind the Mac trick. I know from my Hifi hobby that it's not always a positive thing, bcs the outside fan can actually keep the air from flowing freely, blowing the hot air back where it came from, thus leading to even more build up with heat!

It'll be fine as long as you have it positoned low and aimed upwards. That way, it doesn't block the hot air escaping from the long exhaust vent running along the top.

I have maybe 6 or 7 pre-sets (favorites), including the defaults, in increments up to around 2K, which I never use. Ramping up the fans too high will prematurely burn out the fan motors, or weaken them. That said, fans are a lot cheaper to replace than power supplies, logic boards or drives.

This is the setting I might use when it gets really hot here.

This is the one I rely on most when it gets hot here.

Here are the defaults for my 21.5

I know this won't be much help where you are, but when the inside temp is in the 90s here, I just don't run the computer that often, keeping it sleeping for longer periods, which allows it to cool off. Sleeping the display when not needed will also remove one source of heat, Shift-Control-Eject. Or through Energy Saver, or both.

The external fan at the back is a big help, since the entire aluminum back of the Mac acts as a heat sink. Keeping that cooler, keeps the internal temps cooler, with less need to ramp up the fans as much.

You should also know that running the fans faster will suck in more dust, so keep the area around the Mac free of dust and vacuum peridically. The external fan will also be another source of dust, so after a period of running it, you should wipe the back of the computer down with a dust cloth.

I monitor the temps from the Menubar using iStat Menus.

http://bjango.com/mac/istatmenus/

Kutten1303 wrote:

Thanks, my screenshot from Activity Mon is here, but now the machine is not hot!

Had it switched off in the night, so now i will monitor the Mac every hour or so, while using iTunes, Mail and Safari

It would be better to get a screenshot while you are experiencing the problem. Keep in mind that the problem is NOT temperature. That is a symptom of the problem. Computers do get hot if they are working hard at something. The problem is that your computer may be working hard at something when it shouldn't be.

I ditched TimeMachine, it was completely waste of time, if I hadnt stopped it myself, it would still be running I guess. 4 hours and maybe 30 GB! So I switched to SuperDuper, 250GB in less then two hours, FW800. I have 20GB RAM BTW, there was a discount somewhere. That REALLY is something

That is really another symptom of the problem. Time Machine works very well, but it is more sophisticated than SuperDuper!. If you have a problem somewhere, Time Machine is more likely to be impacted.

It is very important to stop looking at temperature. That is like trying to treat a fever while letting the infection run wild. You have to find out what the problem is, fix that, and then the temperatures will be normal.

It is very important to stop looking at temperature. That is like trying to treat a fever while letting the infection run wild. You have to find out what the problem is, fix that, and then the temperatures will be normal.

I agree that there may be some underlying problem. However, running a computer in 90+ temperatures isn't likely to keep things "normal." We need to ask if the Mac's temperatures have been lower in the past, under the same room temperature. We also need to find out if this only started with ML.

I had also asked for a new screenshot(s) from Activity Monitor while the computer was running hot, not when cool.

I don't think you are alone. Try searching "Mountain Lion temperature hot."

But here is the problem. There is no heater in a computer. There is nothing in an operating system that will just make the computer run hotter. The only temperature controls are fans to keep it cooler. The hard drive will get hot. The CPU will get hot. The GPU will get hot. I/O controllers can get hot. But none of that happens spontaneously. Those components get hot because they are working hard. Why are they working hard? That is the question.

Actually you are totally way off base here. Your whole computer is a "heater" in as much as it consumes "watts" of energy. When the operating system "looks" at more stuff or compares things more often, when the screen size goes from 21" to 27" when the pixels increase by 30% when the bus speed ups 40%... all of these things use more power. It's not magic that things are more detailed and precise in the newer OSs. It's totally the use of more energy (power/watts) that accomplishes that. Watts/energy equals heat unless you have a way of changing the laws of physics.

And why does it consume those "watts" of energy pray tell? Could it be specific components that draw those watts to do work? How does the operating system "look" at stuff or "compare things"? Is there some kind of Central Processing Unit that does that?

It consumes those watts because it is on and working. When the pixels are denser, the CPU has more speed and multiple cores, hyperthreading; it uses more energy.

All those components that are doing the work create heat. No heat ..no work.

The operating system looks at and compares data as per its instruction set. The more complicated the OS, the more work...thus more heat. The CPU certainly does much of the work...more work more heat. What's your point?

My point is that the more complicated and extravagent the output of a system is.. the more work it does the more energy it will consume, the more heat it will produce.

That being said we have reduced power consumption significantly from the first computers ENIAC was housed in a three story structure had a one kilobite processor and dozens of technicians with vacuum tube carts running around replacing defective tubes to keep it running and it consumed 150 kilowatts of electricity to make it work. we still make improvements in power consumption but when comparing similar technologies the more work the greater the heat.