CPU temperature and cooling fan

[HankG]

My HP 794N P4 3.06Ghz, 1 Gig ram and an NVidia Geforce4 MX440 with 128MB
ram, running XP home tends to have an overheating problem. Prior to buying
this one, I purchased an HP P4 2.8, 512 ram, with same video card (Media
Center), which also had an overheating problem, with different symptoms. HP
instructed me to return the computer to the dealer, which is why I wound up
with the latter.

Initially, the problem would occur sometime after I would start a
video-intensive game. The fan would go into overdrive (really loud) and
would not slow down until I exited the game.

Recently, I installed motherboard monitor. Today, it registered a cpu temp
of 132. The temperature dropped to a reasonable (I assume) level (125), but
the fan raced on. It continued to race until I restarted the computer, at
which time it was running normally.

The video card does not have a fan, but rather a heat sink. There is a duct
which is separated from the cpu heatsink and is supposed to pull off the cpu
heat. I question whether the separation is resulting in a 'short-circuit'
and is pulling air mostly from the inside of the box.

The last few days, I have found the computer sitting idle (desktop only)
with the fan racing. The temperature would be in the normal range. Again,
after restarting the idle computer, the fan would run normally.

Hoping some will be able to shed light on the subject.

HankG

 

[Bob]

My HP 794N P4 3.06Ghz, 1 Gig ram and an NVidia Geforce4 MX440 with 128MB
ram, running XP home tends to have an overheating problem. Prior to buying
this one, I purchased an HP P4 2.8, 512 ram, with same video card (Media
Center), which also had an overheating problem, with different symptoms. HP
instructed me to return the computer to the dealer, which is why I wound up
with the latter.

Initially, the problem would occur sometime after I would start a
video-intensive game. The fan would go into overdrive (really loud) and
would not slow down until I exited the game.

Recently, I installed motherboard monitor. Today, it registered a cpu temp
of 132. The temperature dropped to a reasonable (I assume) level (125), but
the fan raced on. It continued to race until I restarted the computer, at
which time it was running normally.

The video card does not have a fan, but rather a heat sink. There is a duct
which is separated from the cpu heatsink and is supposed to pull off the cpu
heat. I question whether the separation is resulting in a 'short-circuit'
and is pulling air mostly from the inside of the box.

The last few days, I have found the computer sitting idle (desktop only)
with the fan racing. The temperature would be in the normal range. Again,
after restarting the idle computer, the fan would run normally.

Hoping some will be able to shed light on the subject.

The cooler that comes with the P4 is inadequate. If you really want to
cool that sucker off, try a Zalman:

http://www.directron.com/cnps7700cu.html

My son put one on and has never had a temperature problem since.


--

Map of the Vast Right Wing Conspiracy
http://home.houston.rr.com/rkba/vrwc.html

"The possession of arms is the distinction
between a free man and a slave."
-- Andrew Fletcher, Discourse on Government (1695)

 

[kony]

My HP 794N P4 3.06Ghz, 1 Gig ram and an NVidia Geforce4 MX440 with 128MB
ram, running XP home tends to have an overheating problem. Prior to buying
this one, I purchased an HP P4 2.8, 512 ram, with same video card (Media
Center), which also had an overheating problem, with different symptoms. HP
instructed me to return the computer to the dealer, which is why I wound up
with the latter.

Initially, the problem would occur sometime after I would start a
video-intensive game. The fan would go into overdrive (really loud) and
would not slow down until I exited the game.

Which fan? CPU fan?

As Bob suggested, a replacement heatsink may be needed, but
I don't know what the current 'sink is so it's a bit hard to
forcast the extent of the improvement.

More often, OEM boxes have be tailored to lower airflow for
noise-reduction (that is, reduction without adding another
fan which would raise construction costs). Adding another
fan and ensuring the airways are open should help- but it
voids the warranty to modify the case.

Recently, I installed motherboard monitor. Today, it registered a cpu temp
of 132. The temperature dropped to a reasonable (I assume) level (125), but
the fan raced on. It continued to race until I restarted the computer, at
which time it was running normally.

We generally use Celsius to report temps. 132F is 55C.
That is higher than many enthusiasts "want", but it is not
atypically high for an OEM box running a 3GHz Prescott.

In other words, you don't have a CPU overheating problem if
it only gets up to 132F. Run a stress test like Prime95's
Torture Test for at least 45 minutes, THEN note the max
temp.

You may still have a system that is louder than you want it
to be, which is quite understandable. A different CPU
heatsink and improved case airflow is still the solution.
If might be possible to attach a larger diameter, thicker
but lower RPM fan to replace your current CPU fan- but not
knowing what heatsink it uses, I can't be sure of it... nor
could the resulting temp be predicted beforehand because of
too many variables.

The video card does not have a fan, but rather a heat sink.

It's not a very hot-running card, it is possible for it to
be cool enough with a passive heatsink. However the best
arrangement is for the adjacent PCI slot to be empty to
maximize flow past it. Another trick is to leave that empty
slot's rear case bracket cover off- which will cause more
passive airflow past the card. However, allowing further
entry points for airflow will reduce the case front intake
rate, which can result in the HDDs running hotter.

There is a duct
which is separated from the cpu heatsink and is supposed to pull off the cpu
heat. I question whether the separation is resulting in a 'short-circuit'
and is pulling air mostly from the inside of the box.

Of course it's mostly pulling air around the 'sink, not
through it- that's typical with most ducted passive
solutions. Even so, that it manages to keep the CPU at 55C
is fairly good. Now it seems as though you have a passive
CPU heatsink, so is it the rear case exhaust fan that is
spinning faster when the CPU temp rises?

The duct will reduce case airflow if it is connected to the
exhaust fan as is typical. By removing that duct the rest
of the system should remain a little cooler- or trimming the
duct back some so it's less restrictive. This may _require_
a different CPU heatsink with a fan on it.

The last few days, I have found the computer sitting idle (desktop only)
with the fan racing. The temperature would be in the normal range. Again,
after restarting the idle computer, the fan would run normally.

It may be a buggy fan throttling implementation. I don't
know if it's solely hard-wired or if there is bios control.
If the latter, you might try updating the (motherboard)
bios. Has the (room) ambient temp risen recently? That
will directly raise the component temps.

The main problem, IMO, is that any alterations you make will
most likely void your warranty, and yet thorough
modifications are the most certain way to effect a permanent
solution. The main variable is how restrictive the case is-
whether it has good front intake and/or can be modified to
improve that, and if you're willing to strip down the system
to do some cutting on your case- if it's even possible, as
OEMs can get rather proprietary in their case designs, some
HP cases even use the front wall of the case to a larger
extent than typical to mount the drive bays- making removal
of front case wall metal a potential issue of structural
integrity.

Mainly it is good to keep in mind that alterations in
airflow should increase the flow in the hottest regions, not
introducing high-flow intake paths if/when there are only
exhaust fans, as it will reduce intake flow in the other
regions.

The ideal arrangement would be a mostly unobstructed front
intake area with the "option" to mount a fan there. Then
the rear duct would be removed or drastically trimmed back.
Then heatsink replaced with one wearing a large thick
low-RPM fan, then replacment of the rear exhaust fan.
Beyond these basics, it depends a lot on the exact design of
the case.

 

[Bob]

Run a stress test like Prime95's Torture Test

Just for comparison, I ran that test and my CPU heated up to 53C and
stabilized. The CPU fan sped up a couple hundred RPM and stabilized.
The case temp went up to 33C and stabilized.

for at least 45 minutes

After 10 minutes of stability, I stopped the test. The duration of the
test was about 20 minutes.

You did not specify which option(s) to choose so I picked the one
which claimed to be the harshest.

Idle temp on the CPU is about 36C. The low measured by MBM5 is 34C. It
never runs any hotter than 40C and that right after I reboot.



--

Map of the Vast Right Wing Conspiracy
http://home.houston.rr.com/rkba/vrwc.html

"The possession of arms is the distinction
between a free man and a slave."
-- Andrew Fletcher, Discourse on Government (1695)