Simviation Forum - Cool down period?

Oct 7^th, 2008 at 12:48pm

Groundbound1 Offline
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This is something I've been wondering about for a while now. I used to drive a turbo-charged car, and I was always told that I should let the car idle for a few minutes after a long or hard trip in order to prevent damage to the turbo.

Should the same care be taken will computers? I mean, let's say you close out a cpu intensive program, and the temp of the cpu is "right up there", would it be better to let the computer idle for a few minutes, allowing the fan to keep reducing the temperature of the processor and heatsink, or just shut the machine down all together, eliminating the workload of the cpu completely, but leaving the heatsink to work passively?

Would either option offer any advantage over the other?

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Reply #1 - Oct 7^th, 2008 at 1:20pm

NickN Offline
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computer and electronics are not a car or the intesnse heat in metals of the internal cumbustion engine

even the thing you were told about turbo chargers is a bit 'off' and would only apply under certain conditions.. and you would have to repeat those conditions for it to have any bearing on long term damage

yes, in theory some of that applies to hot electronics but shutting down a computer when hot will not damage anything worth discussing past 'theory' and nothing to worry about

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Reply #2 - Oct 7^th, 2008 at 2:37pm

Mushroom_Farmer Offline
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The reasoning behind the cool-down period for a turbo-charged engine is to allow the +500°F turbo-charger to cool down. For the purposes of cooling and lubrication oil is circulated through the turbo and shutting down the engine without a cool down will allow the remaining oil to cook inside the turbo. I have seen pyrometer readings of +1200°F on a turbi under heavy load.
Last time I checked, turbo-charged computers aren't cooled by oil. Wink

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Reply #3 - Oct 7^th, 2008 at 4:45pm

NickN Offline
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The amount of heat and of course the oil system would be the primary difference between an automotive engine and a computer however I was looking further into the factors of thermal inversion to molecular fatigue and what happens when high temps are instantly dropped, a very real issue with everything from an automotive engine to silicone based electronics.

Although I also do not see modern automotive technology demanding people sit there and idle their engine to cool off the turbo, racing and of course tech from the past along with aftermarket designs in that respect did play further into that 'idle' recommendation

Under normal driving down a highway with a factory designed modern turbo that is not necessary. The automotive industry mandates different oil and oil change intervals to accommodate the temp issues a turbo charger presents.

If one was to go out and 'horse' on a modern factory designed turbo charged car on purpose, something that the manufacture would not expect the driver to do under normal driving conditions, a need to allow cool down would of course ensue

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Reply #4 - Oct 7^th, 2008 at 6:22pm

Groundbound1 Offline
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Hence the need for aftermarket "turbo-timers".

Obviously, the turbo reference was more of an analogy than a literal comparison, but that was the thought that got my gears turning. Just curious, as I had never heard anything about the subject.

WAY back in the day, I also used to have a computer with a "Turbo" button on it. What should I have done in that case? Huh Huh?! Grin

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Reply #5 - Oct 7^th, 2008 at 6:38pm

NickN Offline
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Groundbound1 wrote on Oct 7^th, 2008 at 6:22pm:

Hence the need for aftermarket "turbo-timers".

Obviously, the turbo reference was more of an analogy than a literal comparison, but that was the thought that got my gears turning. Just curious, as I had never heard anything about the subject.

WAY back in the day, I also used to have a computer with a "Turbo" button on it. What should I have done in that case? Huh Huh?! Grin

better change the oil on that system then

and yes, I understood what you were asking about with the comparison

There is in theory a possibility of thermal inversion issues creeping into the physics of the wafer,.,. AMD is actually more susceptible to that than Intel however its not enough of a problem to worry about shutting the system down directly after high load use.

One other point though.. people who use phase change systems or LN2 would definitely be much more susceptible to those issues which will shorten the life of a CPU due to the over the top temp changes

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Reply #6 - Oct 8^th, 2008 at 2:30am

congo Offline
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Groundbound1 wrote on Oct 7^th, 2008 at 6:22pm:

WAY back in the day, I also used to have a computer with a "Turbo" button on it. What should I have done in that case? Huh Huh?! Grin

I'm pretty sure the "TURBO" button on the old PC's was actually used to trigger a compatibility mode which I have completely forgotten about, but I do believe it actually REDUCED performance.

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Reply #7 - Oct 8^th, 2008 at 8:00am

packercolinl Offline
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I believe a cool down period is valid in a number of areas.

Cooling systems are supplied for a reason and if you are running any system at its maximum cooling capacity and then suddenly deprive it of that capacity you will retain the heat in the system--it has nowhere to go.

I think a cool down period is actually a good thing to practice

Col.

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Reply #8 - Oct 8^th, 2008 at 1:21pm

Mushroom_Farmer Offline
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congo wrote on Oct 8^th, 2008 at 2:30am:

I'm pretty sure the "TURBO" button on the old PC's was actually used to trigger a compatibility mode which I have completely forgotten about, but I do believe it actually REDUCED performance.

Correct. For example, an 80386/20MHz processor will run at 8MHz with turbo off and 20MHz with turbo on. The reason for this is some older programs, like the early versions of Lotus 1-2-3, wouldn't run at the higher speed.

&&&&"We're just sitting here trying to put our PCjrs in a pile and burn them. And the damn things won't burn. That's the only thing IBM did right with it - they made it flameproof." && Spinnaker Software chairman William Bowman, 1985

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