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I'm well aware that overheating is a common source of damage to computers, but can high heat damage them even while powered off? And if it is possible, is it likely?

I ask due to some old components that have been sitting in the trunk of my car for several weeks now, in 90°F+ mid-summer heat, and in the sun. I originally planned on recycling them, and stuck them in the trunk for transport, but today I thought of a new use for them, and I'm trying to decide if they're worth the trouble of re-purposing. If there's a good chance they're fried, then no, they're not.

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Lithium-ion batteries don't like heat, regardless. Not that it sounds like there were any in this instance. – aidan Jul 9 '13 at 1:33
Well some components like the CPU, GPU, and surrounding components can get up to that temperature in Celsius during regular operation, so that temperature in Fahrenheit isn't likely to kill them. Of course there’s other components that are expected to be much cooler normally, which might cook in that heat. Even so, (for future readers) why not just take them indoors, let them cool down, and simply try it out? Worst case scenario, it’s dead (in which case, you can try to figure out which parts are dead and replace them if desired). – Synetech Aug 22 '13 at 20:44
The components in question were not assembled into full machines. They consisted of various parts I'd swapped out during upgrades. And I didn't really want to pull my computer's CPU out again on a "maybe". – user142088 Feb 28 '14 at 23:51
up vote 20 down vote accepted

If the temperature goes above 70-80 Celsius (158 to 176 Fahrenheit) chances are that the capacitors become unstable. A car-trunk in full sunlight can reach that high a temperature.

They can take some heat but not for days on end.

Problem is made worse by old capacitors (old being pre- 2006). They have less tolerance for heat.

Just run the oldest newest of those machines with Memtest86 for 1 hour. If it's unstable it will fail the test.
If one fails I wouldn't bother testing the others and throw the whole batch into recycling.
If it comes through fine you can work your way down the list to older machines or do a binary search.
As soon as you find a bad one you can throw away anything older too.

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Really "the oldest", not "the newest"? (Binary search would be in place, wouldn't?) – Alois Mahdal Jul 8 '13 at 19:58
@AloisMahdal You are right. Stupid mistake on my part. I will edit the answer. – Tonny Jul 8 '13 at 20:16
Solid-state (i.e. ceramic, tantalum, foil) capacitors are not affected by heat as significantly as electrolytic caps. Your answer fails to make that distinction, and seems to refer exclusively to electrolytics. – sawdust Jul 9 '13 at 6:48
@sawdust In my experience pre-2006 caps (on motherboards and in power-supplies) where mainly electrolytes. Starting in 2006 most manufacturers switched to better quality ones. Especially after the bad press they got from the failing main-boards because of bad caps. – Tonny Jul 9 '13 at 14:45
@user555 I mainly meant manufacturing date of mother-board. It sort of amounts to the same thing. See also my comment to sawdust. – Tonny Jul 9 '13 at 14:46

You should be okay if you left them in there one or two times. However, prior to booting them up, I would recommend letting them cool down naturally. Otherwise, you may get condensation built up internally which could cause issues. Same way in the reverse (taking a cold laptop into a warm environment).

Think of it like a cold glass of water, taken outside. Most likely, it will sweat. Laptops do not like to sweat.

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Wouldn't condensation only occur in the reverse - when you bring a cold device to a warm environment? – Philipp Horn Jul 9 '13 at 7:44

If it's enough heat it may melt come capacitors, especially if the hardware (mainly the motherboard) is old, causing shot circuits.

In 32 degrees (Celsius) I don't think it's damaged.

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no, a mid heat summer cannot damage your components. It will work 100% Many components can withstand heat upto 200deg F such as a cpu and a graphics card.

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the CPU isn't the issue here, of course it won't melt. Some capacitors on the motherboard can be damaged from less heat. – matan129 Jul 8 '13 at 19:40
well capacitors can widthstand a significant amount of heat above what op stated around like 60-70C before it starts to loose its charge holding capacity but then that is during runtime. when it cools down from around 60-70C it will function as normal. – Krimson Jul 8 '13 at 19:44
200 degrees (celsius) is highly optimistic. I'd say more like 90-100 degrees for a CPU, and 120 for a GPU (which is typically a bit more resistant to heat). – Thomas Jul 9 '13 at 3:25
Max storage temp for semiconductors is typically 150 degrees C. Electrolytic caps will degrade (and have shorter life span) from excessive heat during operation or in storage. – sawdust Jul 9 '13 at 6:42
@Thomas sry i meant 200deg F as op was working with Farenheight – Krimson Jul 9 '13 at 7:48

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