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PHoynak · Jun 30, 2009, 09:02 PM

I have a Mac Mini 1.66Ghz Core Duo running 10.5.7. Lately I have noticed a lot of flakey behavior (freezes, sluggishness, etc) that a reboot will fix for a while. What can I run to track down what the culprit is?

ghporter · Jul 1, 2009, 05:25 AM

Look at your RAM as the most likely culprit. But first things first: run the hardware tester on your OS X disc and that will help you zero in on the problem. I've never had such problems, but most of the time people post them here, it turns out to be an issue with RAM, either the parts starting to fail or the parts not properly seated.

P · Jul 1, 2009, 05:42 AM

Can also be cooling. Check that the machine is getting enough cool air and that none of the vents are blocked.

I'm not sure that your issue is hardware, though - it may simply be a runaway process doing nasty stuff. Start Activity Monitor (it's in the Utilities folder) and check if some process is using up all the CPU or eating all the RAM when thos slowdowns happen.

PHoynak · Jul 1, 2009, 12:20 PM

My temp shows 74c is that ok?

ghporter · Jul 1, 2009, 02:03 PM

What's that the temperature OF? My iMac currently shows the CPU at 40C and my AirPort card at 69C (the highest listed temperature in iStat).

PHoynak · Jul 1, 2009, 05:58 PM

That's the Cpu temp in iStat. Hopefully it's in F and not C??

adamfishercox · Jul 1, 2009, 06:18 PM

if it says 74 c thats probably celsius... and a problem.

turtle777 · Jul 1, 2009, 10:23 PM

My power supply is 79C (iMac)

But that's not unusual...

For a CPU, it shouldn't be that high.

-t

adamfishercox · Jul 1, 2009, 10:24 PM

My CPU is at 59 C, MacBook Pro.

Simon · 06:08 AM

74C for a CPU is by itself not a problem at all. Under load my Merom C2D regularly shoots up to 90C. It won't trottle until it reaches 100C. If it were to reach 125C ~~120C~~ it would simply shut off to prevent any hardware damage. GPUs get even hotter.

And now during summer time with higher ambient temperatures computers run a bit hotter than usual. Rest assured your Mac will shut itself off if it becomes hot enough for actual damage to occur.

I'd follow P's advice and check ventilation first and then background processes. If you feel your Mac isn't cooling itself down as much as you'd like you can check out the free smcFanControl.

P · Jul 2, 2009, 05:48 AM

Intel laptop CPUs are less sensitive to heat than desktop variants. Desktop Core 2 generally throttles at 60C (well, it's a bit more complicated, as it will throttle at lower temps if the load is low, but 60C is the maximum temp it will throttle at) but mobile CPUs generally go higher. One wiki I found said that the Merom throttle temp is a 100C with catastrophic shutdown at 125C. I can't confirm that, but it sounds reasonable.

Given your temperature of 74C, I suspect a software issue, but check ventilation and do the hardware test first to eliminate those possibilities.

(Throttle means that the CPU will insert noop - no operation - assembler instructions into the instruction stream to slow down the CPU and give it some nanoseconds to cool down between certain operations. This will make the computer feel slower but save it from overheating)

Simon · Jul 2, 2009, 06:03 AM

Although the Mac mini is a desktop, its CPU and chipset are mobile components. That 1.66 GHz CD will work just fine below 100C.

P, you're right about those 125C. I thought it was 120C, but according to Intel's specs it's 125C. Not that I've ever experienced it myself though.

IIRC Penryn (and Merom too I think) can even shut down a core when they pass the 'throttle temp'. Next to dropping the clock that's probably the easiest way to reduce dissipated power short of shutting off the entire CPU.