P4 cooling question

[Darkfalz]

I have two 6cm rear exhaust fans and one front 8cm case fan, and it seems my
cooling works okay. Before I put the rear fans in, my P4 CPU fan would
sometimes get up as high as 5500 rpms under stress, which made a loud high
pitched whine that drove me nuts.

Now the fans are there, the CPU fan is not going above 4000 rpms under
stress even on a hot day (it's nearly summer in Australia), but the thing
that confuses (and worries) me is that it takes an eternity for it to go
back down (to about 2700 rpms) when the system is no longer under stress.

It's like the fans keep it from getting too hot under heavy load, but don't
do much to cool it down afterwards.

On my old P3 based system, the temperature would drop fairly rapidly when
the system went back to being idle.

Is this normal and if not, is there anything I can do about it?

 

[GHalleck]

I have two 6cm rear exhaust fans and one front 8cm case fan, and it seems my
cooling works okay. Before I put the rear fans in, my P4 CPU fan would
sometimes get up as high as 5500 rpms under stress, which made a loud high
pitched whine that drove me nuts.

Now the fans are there, the CPU fan is not going above 4000 rpms under
stress even on a hot day (it's nearly summer in Australia), but the thing
that confuses (and worries) me is that it takes an eternity for it to go
back down (to about 2700 rpms) when the system is no longer under stress.

It's like the fans keep it from getting too hot under heavy load, but don't
do much to cool it down afterwards.

On my old P3 based system, the temperature would drop fairly rapidly when
the system went back to being idle.

Is this normal and if not, is there anything I can do about it?

Probably normal. Most P4 fans are equipped with its own thermal control
and it might take a bit more time for the fan control to equilibrate than the
readout that is taken from the thermal diode built into the CPU.

 

[Darkfalz]

Probably normal. Most P4 fans are equipped with its own thermal control
and it might take a bit more time for the fan control to equilibrate than the
readout that is taken from the thermal diode built into the CPU.

Once it goes above 3000, it doesn't seem to go back under it again unless I
power down.

Even though my CPU temp is only 36 C right now (same as motherboard temp)
and has been for an hour, the fan is still hovering around 3400 rpm.

 

[Tim]

hi,
if you want quiet, get a zalman 7000 ALCU.
You don't say what mobo you have, so double check it will fit.
I have one on a P4 2.8C and with the fan on low speed it idles at 33c and is
inaudible over the disc drives.

The temp on yours is good, but why put up with the noise?

- Tim

 

[Nick (no dashes)]

hi,
if you want quiet, get a zalman 7000 ALCU.
You don't say what mobo you have, so double check it will fit.
I have one on a P4 2.8C and with the fan on low speed it idles at 33c and is
inaudible over the disc drives.

The temp on yours is good, but why put up with the noise?

- Tim

Before I even read this reply I was planning to tell you to get a Zalman!

I have a P4 2.8c and fitted a Zalman 7000A-Cu yesterday. Right now, In
Sydney my case temp is 39 and CPU is 34. The highest temp I have seen
with the Zalman is 49 and that is with the CPU overclocked to 3.06 and
the serious heat we had today (I saw that at 5pm - my unit was tres hot
as the windows were all shut).

With the stock fan my CPU would have been in the 60's and idled in the
50's. Early this morning it was 31 while I was working.

The Zalman just knocked a strait 15 or so off the CPU heat. That's also
with a FX 5900 card in the case, which is a pretty warm card.

Also, it is absolutly silent - even when running fast - although right
now it's at 1800rpm.

 

[Ghostrider]

Once it goes above 3000, it doesn't seem to go back under it again unless I
power down.

Even though my CPU temp is only 36 C right now (same as motherboard temp)
and has been for an hour, the fan is still hovering around 3400 rpm.

GH probably did not notice that the motherboard is an Asus. If the Q-Fan
setting has been enabled, then the motherboad CPU fan controller and the
built-in heatsink fan regulator are opposing each other. Disable Q-Fan.

 

[Darkfalz]

GH probably did not notice that the motherboard is an Asus. If the Q-Fan
setting has been enabled, then the motherboad CPU fan controller and the
built-in heatsink fan regulator are opposing each other. Disable Q-Fan.

I never enabled it in the first place.

 

[Dan Smith]

To Darkfalz and anyone else who may be able to help:

I recently purchased a P4 (3 ghz), and the whine that the fan gives off has
been driving me NUTS. The speed changes intermittantly and after 20 or 30
minutes of use it starts to sound like a barely muffled vacuum cleaner. I
have to turn my computer off at night because the whine is so loud it
sometimes disrupts my sleep; it is also extremely annoying if I am trying to
watch a movie or read a book in the same room.

Just a few minutes ago, I opened my computer up and unplugged the fan that
is directly over the CPU, just to see what it would sound like without it. I
tried to remove the CPU fan but it wouldn't come off easily and I didn't
want to break anything-- so I just unplugged it from the motherboard. My
computer is running now very smoothly and quietly with two small fans, one
attached to the back and one attached to the side (opposite the
motherboard).

Is this a bad idea? Is the fan over the CPU in danger of melting because it
is not running and is so close to the CPU?

What are my other options for fixing this noise problem? If I plug the CPU
fan back in AND put more small fans inside the computer, will that keep the
CPU fan running quieter? Can someone recommend a good brand of computer fan
that is both powerful and quiet?

Also, how do I measure the RPMs of my fans as Darkfalz makes reference to
below?

Any help is GREATLY appreciated!

Dan

 

[David Schwartz]

Just a few minutes ago, I opened my computer up and unplugged the fan that
is directly over the CPU, just to see what it would sound like without it. I
tried to remove the CPU fan but it wouldn't come off easily and I didn't
want to break anything-- so I just unplugged it from the motherboard. My
computer is running now very smoothly and quietly with two small fans, one
attached to the back and one attached to the side (opposite the
motherboard).

Is this a bad idea? Is the fan over the CPU in danger of melting because it
is not running and is so close to the CPU?

Yes, this is a bad idea. The CPU could get hot enough to damage itself.

What are my other options for fixing this noise problem? If I plug the CPU
fan back in AND put more small fans inside the computer, will that keep the
CPU fan running quieter? Can someone recommend a good brand of computer fan
that is both powerful and quiet?

Replacing the fan with a high quality fan will likely help. It sounds
like your fan is not just noisy but broken, perhaps someone pushed too hard
on it or the bearings are failing. Get a good ball bearing fan and you'll be
quite happy. Get a friend (or computer store) to do the fan swap.

You may wish to get a new heatsink/fan combination because that's a good
way to make sure the fan and heatsink will work properly together and the
fan will fit. Again, let a friend do it. It's easy to break things or get
the thermal interface wrong.

Take a look at these (these may not be the best prices, and no
endorsement of these products or suppliers is intended, these are just to
give you an idea of what's available):

http://www.bestbyte.net/Product.cfm?ProductID=1115&CategoryID=6&Keyword=
http://store.yahoo.com/uricom-com/noname13.html
http://store.yahoo.com/uricom-com/vac7soa478ae.html
http://store.yahoo.com/uricom-com/vac7soa478ae.html
http://65.174.51.5/cgi-bin/sundial/di47h53d.html
http://www.ewiz.com/detail.php?p=FAN-VA476&c=pw

If you decide to just get a new fan, Vantec makes extremely quiet fans.

Also, how do I measure the RPMs of my fans as Darkfalz makes reference to
below?

Your motherboard should measure it and most include software to access
that information. If not, there are programs like motherboard monitor and
speedfan that will tell you. You want to stay below 55C or 130F. Remember,
CPU temperature will go up more or less with room temperature, so if you're
CPU is at 120F when your room is at 70F, your CPU will hit 130F when the
room hits 80F.

It's a very good idea to get a program that lets you monitor CPU
temperature especially if you're going to mix and match heat sinks with
fans! (It can be done and you're usually okay, but you want to make sure.)

DS

 

[David Wang]

Yes, this is a bad idea. The CPU could get hot enough to damage itself.

You deleted the part where Dan says that this is a 3 GHz P4.

P4's won't get hot enough to damage itself. It has built-in
thermal thorttling circuitry that slows down the operating
frequency of the processor when the thermal threshhold is
reached. When you run such a processor without the fan and you put a
serious workload on it, the processor will constantly throttle, and
the 3 GHz P4 may perform no better than a 1.6 GHz P4, but it won't
damage itself.

IIRC, there's a web page somewhere that the tester ran the processor
without a fan or heatsink, and the system still worked just fine,
albeit at a lower performance.

 

[Dan Smith]

That's good to know David, thanks. My CPU fan is plugged back in and loud
as ever.

I installed Motherboard Monitor and my CPU is running at ~105F, so
apparently I just have a shoddy CPU fan. People in this group and elsewhere
seem to continually recommend the Zalman CNPS7000-ALCU, which I will likely
purchase. Thanks for your help.

Dan

 

[Strontium]

It's a great heatsink/fan. And very quiet, even at full fan RPM.

-
Dan Smith stood up, at show-n-tell, and said:

 

[David Schwartz]

P4's won't get hot enough to damage itself. It has built-in
thermal thorttling circuitry that slows down the operating
frequency of the processor when the thermal threshhold is
reached. When you run such a processor without the fan and you put a
serious workload on it, the processor will constantly throttle, and
the 3 GHz P4 may perform no better than a 1.6 GHz P4, but it won't
damage itself.

The thermal throttling may or may not be enabled. As I understand it,
the throttling can run at no lower than 1/2 duty cycle. With no fan, at a
high workload, and with a high ambient temperature, even half duty cycle can
allow the processor to get hot enough to fail permanently.

IIRC, there's a web page somewhere that the tester ran the processor
without a fan or heatsink, and the system still worked just fine,
albeit at a lower performance.

With what workload? With what ambient temperature? I definitely wouldn't
trying this at home.

DS

 

[David Wang]

With what workload? With what ambient temperature? I definitely wouldn't
trying this at home.

http://www.tomshardware.com/cpu/20010917/index.html

 

[Paul]

To Darkfalz and anyone else who may be able to help:

I recently purchased a P4 (3 ghz), and the whine that the fan gives off has
been driving me NUTS. The speed changes intermittantly and after 20 or 30
minutes of use it starts to sound like a barely muffled vacuum cleaner. I
have to turn my computer off at night because the whine is so loud it
sometimes disrupts my sleep; it is also extremely annoying if I am trying to
watch a movie or read a book in the same room.

Just a few minutes ago, I opened my computer up and unplugged the fan that
is directly over the CPU, just to see what it would sound like without it. I
tried to remove the CPU fan but it wouldn't come off easily and I didn't
want to break anything-- so I just unplugged it from the motherboard. My
computer is running now very smoothly and quietly with two small fans, one
attached to the back and one attached to the side (opposite the
motherboard).

Is this a bad idea? Is the fan over the CPU in danger of melting because it
is not running and is so close to the CPU?

What are my other options for fixing this noise problem? If I plug the CPU
fan back in AND put more small fans inside the computer, will that keep the
CPU fan running quieter? Can someone recommend a good brand of computer fan
that is both powerful and quiet?

Also, how do I measure the RPMs of my fans as Darkfalz makes reference to
below?

Any help is GREATLY appreciated!

Dan

http://www.zalman.co.kr/english/product/cnps7000a-cu.htm (pure copper)
http://www.zalman.co.kr/english/product/cnps7000a-alcu.htm (mixed design)

The biggest and quietest HSF is the Zalman CNPS7000. There are two models,
a pure copper one and a mixed copper/aluminum one. The pure copper design
idea is best for chips without a heat spreader (like an Athlon), while the
AlCu mixed design is best for chips with a heat spreader (like the P4).
The pure copper one acts as a heat spreader, for CPUs that don't have
their own heat spreader.

There are a couple of downsides with this device - it may not fit all
motherboards (it may even bump into the power supply), and the mass is
higher than the design goal of 450 grams. The CNPS7000 uses the P4
bracket as an anchor.

If you plan on moving the computer around a lot, a more rugged solution
is a Swiftech MCX4000. It is a copper plate that bolts to the holes in
the motherboard.

http://www.swiftnets.com/products/mcx4000.asp

By securing the heatsink to the board, there are no worries about the
P4 bracket being sheared off.

The downside of the MCX4000 is it wouldn't be as quiet as the Zalman.
This is because the airflow is purposefully chaotic and the design has
a much higher arrestance than the Zalman design. But it definitely
won't be falling off. Because a fan is not provided with the heatsink,
you can buy one of the several models of Panasonic Panaflo sealed
sleeve bearing fans, to get a quiet solution. (The catalog I was
looking at has low, medium and high speed Panaflo models, and the
one you select will depend on what thermal load you expect to be
cooling.)

With the Zalman, you don't even need to thermally control the fan.
The fan can be connected directly to +12V and run at full speed all
the time - you still won't hear it (at least judging by the dB numbers
quoted for it in reviews).

The Zalman is cheaper to make, because it is made from a series of metal
plates that are compressed together. The Swiftech products tend to be
milled from solid blocks of metal.

HTH,
Paul

 

[David Schwartz]

http://www.tomshardware.com/cpu/20010917/index.html

Something's odd here. In use, no temperature anywhere on a CPU is going
to be below the ambient temperature and, in general, under comparable load,
if you replicate the temperature in one place on a CPU, the temperatures in
the other places will be the same as well.

So if I run Quake 3 Arena on a P4 in an ambient temperature of over 84
degrees F, my surface temperature will definitely exceed 84 degrees F
regardless of how good my heat sink and fan are. If the spreader is the same
84 degrees and the CPU heat generation is the same (because the workload is
the same), then I should experience a slow down as well. From which it
follows that at 85 degrees F ambient, a P4 will throttle regardless of how
good the heat sink / fan is.

I don't think that's likely given how much higher than that the maximum
operating temperature of the chip is and how low the thermal resistance is
between the wafer and the heat spreader.

DS