>> Actually, it is recommended that the cover always be on. There arefour
>> factors reasons for keeping the cover on: 1) Demetri is correct, thecase
>> is designed to create airflow where it is needed, without the cover,the
>> flow changes and may not cool properly.
>Personally disagree any manufactry's claim on "case is desinged to create
>airflow" issue, unless multi-case fans have been carefully placed inright
>position, and capable to create correct aireflow between fans, 99% case/fans
>I've seen failed to create correct airflow, or does not create "airflow"at
>all. I've been working with many brand of cases, only top priced casemay
>create little "airflow" with power supply fan only, or mis-placed 2ndcase
>fan, of course expensive sever case can provide good airflow. in orderto
>create airflow to help on heat problem, at least one case fan shouldwork
>closely to mobo/video/cpu area and at least two fans should be used,one
>blow cool air in, one such hot air out, and they should be placed at>>
position that are not blocked by anything. most cases don't have 2ndfan,
>even they do, the 2nd fan is usually placed at bottom of case which
does
>almost nothing to help on heat issue.
Jun Qian
darn, you guys know so much about these things that i'm in awe when i
read these postings -- and extremely grateful. but i think i gotcha on
one. if i'm wrong here, let me know where.
you don't need two fans. on the first floor of my house i use an exhaust
fan on the enclosed back porch. all the windows are closed except one
in the front room. the fan draws air through the house, cooling all the
rooms.
a second fan blowing in in the living room would increase air flow and
cooling, but so does increasing the speed of the fan on the back porch.
creating negative air pressure means that air will enter, if it has a
way.
virtually every upright computer case i've seen has an exhaust fan at
the top rear and intake vents at the bottom front and perhaps bottom
side edges(yes, i've heard of ones that have fans blowing in at the top
rear. i agree that that's bad design). the air flow passes nicely through
the case, across the cpu, near or across the hd and across most of the
mobo -- altho the video card sometimes is in a dead area. the fact that
the air is picking up heat as it cools components means that it tends
to rise toward that exhaust fan, adding to the efficiency of the system.
if a second fan is used, it should be an intake fan and belongs at the
bottom of the case in the front, boosting the case's natural corner-to-corner
and upward airflow.
supposing one wants to run a computer with the case off (there's an old
dell beside my feet that has run that way for almost 5 years, as faultlessly
as the other old dell beside my right elbow that has run just as long
with the cover on). then the fan will add virtually nothing to cooling
except for the power supply, because air from outside the case, which
is nearer the power supply intake than the air that's beyond the cpu/mobo
-- will flow into that negative pressure area. other components will
get no
benefit from the fan. so perhaps if the power supply is well-enough ventilated
and well-enough made, you don't need a fan at all if you run cover-off.
i think this makes sense, altho i have no idea whether critical components
actually run cooler with the cover off or on. i guess the only way to
really know would be to measure the temp on a bunch. i don't have an
appropriate thermometer, tho.
--
bob raikes
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