Re: [PCWorks] What's a heatsink? (Was Re: Thanks to list members, and KEEP the posts coming!)
- From: David Grossman <dgrossman@xxxxxxxxxx>
- To: pcworks@xxxxxxxxxxxxx
- Date: Sat, 04 Apr 2009 22:27:55 +0300
Sue,
In ye olde days, back when people like me had hair, serious computers were
maintained in big rooms with air conditioners. I recall working on a PDP-11,
and some of the senior members of this group may remember even bigger
monstrosities.
Yes, smaller and relatively pathetic computers did not need air
conditioners, but any business or academic computer (that only had a
fraction of the oomph and storage of today's computers) needed big,
expensive air conditioners. Even so, the rooms were quite warm. Those air
conditioners were rarely serious competition for the heat emitted by the
computers.
Today's computers (and especially parts such as the microprocessor) still
emit a great deal of heat, even though they no longer use vacuum tubes. As a
computer teacher, I work in an air-conditioned computer lab, but it
sometimes gets uncomfortably hot in the summertime.
Put your hand behind your computer, and you'll feel hot air from the
computer fan. That's one way of making the computer cooler. Another way is
the heat sink that Clint described. The fan and the heat sink do not cool
the computer, but they make it usable.
This information is not to be confused with those computers that REALLY
heated up a few summers ago. Their Sony batteries actually caught fire.
However, that's material for another thread.
David Grossman
> -----Original Message-----
> From: pcworks-bounce@xxxxxxxxxxxxx
> [mailto:pcworks-bounce@xxxxxxxxxxxxx]On Behalf Of Clint
> Hamilton-PCWorks Admin
> Sent: Saturday, April 04, 2009 3:00 PM
> To: pcworks@xxxxxxxxxxxxx
> Subject: [PCWorks] What's a heatsink? (Was Re: Thanks to list
> members, and KEEP the posts coming!)
>
>
> (I forgot to change the subject line of Sue's post to the
> appropriate topic, so I'm doing that this time).
>
>
> Technically, a device, usually metal, that draws heat away from
> either a heat-sensitive device and/or a device that produces
> large amounts of heat, to facilitate faster more efficient
> cooling of the hot device.
>
> In this context, it's a HSF unit (heatsink & fan) which MUST go
> on the motherboard's CPU (aka processor), or the CPU will melt
> (or, theoretically they are supposed to shut down via thermal
> protection before it melts). There are usually HS's all over a
> motherboard, and video card. Some of them will have fans on
> the HS if the HS is too small or if the device gets too hot for
> a HS alone. Years ago, you never saw any HS's on a mobo (aka
> motherboard), and the CPU only needed a HS and not even a fan.
> But the faster the chips operate, the hotter they get,
> therefore the need for HS's, and larger and larger ones.
>
> It order for a HS to work properly, it's surface ideally should
> be mirror-smooth, as should the surface of the HS, and tightly
> and squarely attached at perfect right angles to each other.
> If there are any surface imperfections, the more of them that
> exists the worse the HS will perform and the hotter the device
> will get. If they are smooth enough down to the atomic-level,
> no TIM (thermal interface material) is needed. But since the
> two surfaces can never be like that in practical use, even
> after lapping, hence the requirement of good TIM. ("Lapping"
> is a multi-stepped VERY fine sanding process on both CPU and HS
> surfaces in efforts to achieve these perfect mirror-smooth
> surfaces). Ideally, TIM fills all the surface imperfections,
> creating a greater contact area for better cooling. The
> greater the contact area, the better the cooling. TIM can be
> silicone based (not very good), or have copper or silver
> particles in it, or PCM (phase-change material), or thermal
> pads. There's a huge market of TIM, dozens and dozens of
> various patented formulas, with more coming out each year.
>
> Lapping can't really be done on non-metallic chips, like
> transistors, FET's (Field Effect Transistors) or IC's
> (Integrated circuit chips) because they are usually silicon or
> similar material (that can operate a high temps), and you can't
> exactly sand those. With those that require a HS, you usually
> need more TIM to cover the greater surface imperfections. To
> much TIM can actually be a thermal INSULATOR, which of course
> is bad. So you always want to use as little as possible.
> -Clint
>
> God Bless,
> Clint Hamilton, Owner
> www.OrpheusComputing.com
> www.ComputersCustomBuilt.com
> www.OrpheusComputing.com/PCworks-computer-help-email-list.html
>
>
> ----- Original Message -----
> From: "Sue Cubic"
>
> At 10:05 AM 4/3/2009 -0500, you wrote:
>
> >There was a time when I didn't know the difference between a
> >hard drive (HDD) and a floppy drive (FDD), and didn't know
> >that
> >a CPU needed a heatsink!
>
> Ok, Clint. I'll bite. What's a heatsink?
>
> Sue (computing since 1986, and never knew I needed one!)
>
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