Swampy wrote:
> My cooling case fan died, but my Dell doesn't like the one I replaced it
> with. The measurements are okay and the spec are in the ball park. I
> couldn't find one locally that matched the one that died. Actually, I did
> take the old one with me. Dell pcs sure are picky!
>
> Questions are:
> Who makes the Dell cooling fans?
> Does anyone have any ideas on this issue? I didn't find any fan info on the
> Dell support site. I'll probably have to order an appropriate fan online.
>
> Thanks, anyone!
>
The existing CPU fan, probably has an RPM signal on it. Many cheap case
fans (at least the ones I can get around here), have only two wires, and
are missing the RPM signal. If used in a CPU cooling application, a fan
with a missing RPM signal, will be detected by the computer BIOS. The
BIOS may shut the computer off, if it thinks the fan is stuck (no RPM
pulses).
http://support.dell.com/support/edoc...ce.htm#1101572
CPU fan connectors come in two types. The old style had three pins
(+12V, GND, RPM). The new style have four pins (the extra pin is PWM,
so the computer can send a signal to the fan, to tell it how fast
it is supposed to run). Whether a three pin or a four pin connector
is used, the BIOS will still be monitoring the RPM signal.
You can plug a three pin fan, onto a four pin header. The PWM signal
will not be connected, if you do that. It means the motherboard cannot
turn down the fan if it wants to. A fast running fan keeps things cool,
so that is not a problem. Only the noise from the fan, may be a problem
for the user.
Chances are, at retail, you'll be able to find a three wire fan. So it
won't have PWM. You'll still have to check, to see if the fan has two
wires or three wires, and one with two wires (no RPM) would be a bad choice.
I know around here, if I wanted such a fan, I'd probably have to order it
from the Internet, to get something decent.
When it comes to computer case fans, some product lines come in four
operating speeds. L,M,H,U. (Low, medium, high, ultra, or something to
that effect.) Low or medium would be not too noisy, and pretty pleasant
to deal with. High or Ultra, would move plenty of air, and are useful
for cooling large thermal loads. You have to guess at what you
think the current fan type is, to get a rough match for its performance.
If you use too slow a fan, the CPU may get warmer than it is supposed
to, and it will throttle back in response to the overheating.
So you have a few criterion for shopping:
1) At least three wires, so there is an RPM signal for the CPU fan connector.
2) Standard size, measured to match the current fan. For example, 80x80x25
or 92x92x25 (mm).
3) A match for performance level, somewhere between silent (L) and
cyclone (U).
4) PC fans run on 12VDC for case cooling or CPU cooling. You may see
some other voltages, like 24VDC listed, but you don't want that.
5) Fans come in sleeve bearing and ball bearing. Sleeve bearing
can be the cheapest kind, and some can wear out (become noisy)
in a matter of a few days.
Shopping for fans is actually pretty annoying. For every two I buy,
I end up using only one of them. And that is because you don't get
to test them, to find out what they'll be like. I've even had some
that had an offensive smell, and they had to stay in the box they
came in.
HTH,
Paul
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