Actually, it is recommended that the cover always be on. There are four
factors reasons for keeping the cover on: 1) Demetri is correct, the case
is designed to create airflow where it is needed, without the cover, the
flow changes and may not cool properly. 2) Computers radiate, and are
susceptible to "Radio Frequency Interference" or RFI.  3) Computers
radiate, and are susceptible to "ElectroMagnetic Interference" or
EMI.   Many states or provinces strictly govern how much "noise (RFI or
EMI)" is allowed to escape from a computer, and leaving the cover off will
definitely violate all such regulations.   4) The cover also keeps the
computer cleaner, at least it should ;-)   I just cleaned two years of fuzz
out of mine YUCK.
   Hope this helps.

At 10:40 PM 9/4/2000 +1000, you wrote:
>There should be study on this topic, "which is better? cover off or on".
>Here is my $0.02
>SDRAM is not recommended by Intel and RAMbus, but it turned out that
>expensive RDRAM is even worse than SDRAM.
>No business will like customer run pc without case, it is not good looking
>(true, many people buy computer because it looks cute, especialy women,
>that's why pc OEMs are using more and more funcy looking, cool case which
>doesn't do any good to reduce heat or provide more space or make things easy
>to handle), and dust will be problem if you don't clean often. For normal
>home PC, nothing can be more effective to reduce heat problem than open the
>case cover and place a fan to blow air to it (from side). a true computer
>user doesn't care how the looking outside (only apply at home, office is
>totally different environment).
>I have a friend who like to overclock, his computer has a little chance to
>have cover on, massive CPU fan, and cover off are the key issues to keep his
>computer running stable, if a overclocked system runs better with case off,
>why not the normal un-overclocked systems?
>Today's harddisk become hotter and hotter (faster and faster), without
>proper cooling, harddisk will have much shorter life. leave cover open is
>better or at least as good as spend $50 to get a good harddisk fan.
>But again, leave the cover open will not give you a cute looking computer (I
>read from the old paper, "why you buy a iMac?", the most common answer from
>women are "it's cute, sexy look, really catch my eye, ...". anyway, I don't
>understand what is sexy for a computer), and you have to clean the cpu fan
>often.
>
>I guess I'm too close to gamers and overclockers side ...
>
>Jun Qian
>
>----- Original Message -----
>From: "Demetri Kolokotronis" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Monday, September 04, 2000 1:04 AM
>Subject: Re: [PCBUILD] Mobo/Processor Overheat
>
>
> > I read this was not recommended, as running with case closed provides
> > flow channels for fans. System has two case fans, plus processor fan.
> >
> > Demetri Kolokotronis
> >
> > On Sun, 3 Sep 2000 23:38:34 +1000 Ultra <[log in to unmask]> writes:
> > > For temp solution, open the case, leave the computer run without
> > > cover, this will buy sometime until you can replace/add new fan for the
> >
> > > case and/or cpu. you can run computer without cover (I do when
> > > summer time comes in and it's hot day), as long as you clean cpu fan
> > > every half month.
> > >
>
>          PCBUILD maintains hundreds of useful files for download
>                      visit our download web page at:
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         PCBUILD maintains hundreds of useful files for download
                     visit our download web page at:
                     http://nospin.com/pc/files.html