Power supply fan airflow direction

On Wed, 25 Jun 2003 01:07:30 +0200, Halfgaar
wrote:


I'll consider the extra fan option, but I'm not sure. I've been doing a
little experimentation with other computers. One of my other computers
creates quite a substantion airflow without much noise, I can also feel in
intake draft very well at the holes in the back of the PSU. With this PSU
there is hardly even intake airflow with the original fan. This PSU is
packed with components (the one from that other computer is not), so I
guess it's preventing airflow and increasing turbulence.

It has small air inlet holes or slits? Most decent 300W PSU have
quite open areas on the back, or a fan underneith, or both.




If, when you write "cover of my case is off, the PSU stays luke-warm",
you mean that the PSU casing is warm, then the PSU is running too hot.
The casing of an fan-cooled PSU should not get warm, except in rare
instances when the power supply's heatsinks are futher 'sinked to the
PSU chassis... this is more common in proprietary-shaped or 1U and
redundant PSU, but not common in PC PS2 sized PSU.

I indeed meant that the PSU casing is warm, but not much. But I can't
imagine that it's suppose to stay cold. I believe that even with the
original fan it got warm. Perhaps all the compontents inside I talked about
above prevent good airflow. Maybe I should be looking for another PSU.

"Warm" may be a relative term, but normally a PSU casing isn't going
to be more than a very few degrees above the case air temp. As I
mentioned before, you'll have to decide for yourself if you're willing
to reduce the lifespan of the PSU for reduced noise. It is clear that
a cooler-running PSU will last longer, and the hot air may also be
unkind to the Pabst sleeve-bearing fan. (IIRC, their 12db model uses a
sleeve-bearing, right?)


BTW, I've made some changes to my fan-setup. I now have my intake fan
mounted differently. My case temp is 32 degrees C now, afters hours of
being mostly idle, with an ambient temp of 25 C. That is a reasonable temp,
is it not?

Halfgaar

Case temp is within normal range, but when you reduce airflow more
attention needs be paid to the thermally-sensitive parts that don't
have temp sensors. Ultimately only you can make the final call.


Dave

kony wrote:

Now we're getting somewhere... I had an MSI
K7T Turbo and still have a K7T Turbo2. There's no quesiton about it,
the sensor is in the southbridge. No sensor below the AGP or anywhere
else, just the Southbridge. As for why your Linux program mislabeled
them, well that's common, there's just a few temp monitor "circuits"
and they are often in reversed labeled "positions" in misc apps...
same goes for the fan RPM sensors. The Southbridge reading is not an
accurate representation of the system temp, is more related to how
close the voltage levels are to spec, and how much air is flowing
directly over the southbridge. The southbridge needs no heatsink, but
if you were to attach a fanned heatsink similar to on a northbridge,
you could watch the temp drop as a result, it would more closely
represent the ambient case temp but still be a bit higher.

Funny you should mention "a fanned sink like on the northbridge". My
northbridge only has a sink and it gets finger-burning hot. It doesn't seem
OK to me, but it's what MSI decided to do.
And you're right about the mislabling, the fan labels were also swapped. So
I guess your right about my systemtemp sensor too.


I wouldn't worry about those temps, they seem fine, but you might take
note of the temps on the capacitors next to the row of voltage
regulators onboard (touch-test them). If they're more than slightly
warm expect them to have reduced lifespan. When I got my Turbo2 I put
heatsinks on the regulators, a socket 7 'sink on the northbridge, then
sort of "draped" the fan half on the northbridge 'sink and half
hanging off to the left of it, to move air through the 'sinks for the
regulators. You may not need to do this, I was taking precautionary
measures prior to highly overclocking a Palomino Athlon in a small
case.

At least two caps on my board get very warm, not finger-burning, but still
quite warmer than the rest.

Putting a second fan on the power supply should be sufficient to keep
the top of the case cool, providing there's an adequate air inlet.

Intake air is supplied by a 12 cm fan at 1300 RPM, not very very much, but I
don't think that's going to be a problem.

If you don't mind (and if you do ), I'll answer some questions of your
other reply here as well:

My 300W powerman PSU has a few small inlet slots at the back and the side
and many of them are covered by components inside. I think what I must do
is get myself a powerfull PSU really built for low noise but still produce
a good airflow, like the one in my other computer I talked about. This PSU
is also labelled as "low noise" but the only reason for that seems that it
has a fanspeed controller which lets the fan spin faster if it's hotter.
Not that it helps, because it only slows down the fan when the PSU is
practicly freezing.

About the livespan of my hardware, I care about long livespans. I also make
sure I don't turn my computers or other electronic devices on and off many
times, to prevent power surge damage.
But I also like low-noise. I think I have to mix the two in this case.

And about the papst, I must say that I don't know what bearing it has. I had
thought a ball bearing, because in my experience only very cheap fans use
sleeves, but you're making me doubt.

Halfgaar
--
To send email, change nospam.com into yahoo.com.

On Thu, 26 Jun 2003 00:42:36 +0200, Halfgaar
wrote:


Funny you should mention "a fanned sink like on the northbridge". My
northbridge only has a sink and it gets finger-burning hot. It doesn't seem
OK to me, but it's what MSI decided to do.
And you're right about the mislabling, the fan labels were also swapped. So
I guess your right about my systemtemp sensor too.

My Turbo2 also had only the tiny 'sink, but since it sits on the board
at a somewhat 45 degree angle, it allowed a few slow 60mm fan to be
mounted diagonally across half of a traditional 40-50mm 'sink... half
the reason I changed the 'sink was so I had a nice location to mount
the fan for cooling the voltage regulator/capacitor area to the left.
I was using a relatively low-CFM CPU heatsink fan so a bit of extra,
directed airflow did seem to help.

Hmmm, I just realized something, I've been getting my MSI motherboad's
names mixed-up... I was thinking of a K7T266 Pro2 half the time, and
the other half I was thinking about a K7T Turbo2 (I've had both). The
Turbo2 already had heatsinks on the voltage regulators from the
factory, and was unusual in that it used a 12V P4 connector for CPU
power. What I previously described about "draping a fan" to cool the
reguloators/caps, was on the K7T266 board. On the K7TTurbo2 I cooled
the northbridge passively, used 1/3 of an old P2 Katmai heatsink, cut
off.. was one of those OEM-passive-type with really tall tines. It
must've done well enough, I recally that the board was stable over
150MHz FSB, around which point the USB ports crapped out.

I wouldn't worry about those temps, they seem fine, but you might take
note of the temps on the capacitors next to the row of voltage
regulators onboard (touch-test them). If they're more than slightly
warm expect them to have reduced lifespan. When I got my Turbo2 I put
heatsinks on the regulators, a socket 7 'sink on the northbridge, then
sort of "draped" the fan half on the northbridge 'sink and half
hanging off to the left of it, to move air through the 'sinks for the
regulators. You may not need to do this, I was taking precautionary
measures prior to highly overclocking a Palomino Athlon in a small
case.

At least two caps on my board get very warm, not finger-burning, but still
quite warmer than the rest.

I do recall some people reporting that a couple of caps right above
the AGP slot were prone to failure, the one in the middle and the
other next to the memory slots, right below the northbridge.



Putting a second fan on the power supply should be sufficient to keep
the top of the case cool, providing there's an adequate air inlet.

Intake air is supplied by a 12 cm fan at 1300 RPM, not very very much, but I
don't think that's going to be a problem.

If you don't mind (and if you do ), I'll answer some questions of your
other reply here as well:

My 300W powerman PSU has a few small inlet slots at the back and the side
and many of them are covered by components inside. I think what I must do
is get myself a powerfull PSU really built for low noise but still produce
a good airflow, like the one in my other computer I talked about. This PSU
is also labelled as "low noise" but the only reason for that seems that it
has a fanspeed controller which lets the fan spin faster if it's hotter.
Not that it helps, because it only slows down the fan when the PSU is
practicly freezing.

About the livespan of my hardware, I care about long livespans. I also make
sure I don't turn my computers or other electronic devices on and off many
times, to prevent power surge damage.
But I also like low-noise. I think I have to mix the two in this case.

And about the papst, I must say that I don't know what bearing it has. I had
thought a ball bearing, because in my experience only very cheap fans use
sleeves, but you're making me doubt.

Halfgaar

Here's a Pabst spec sheet that seems to indicate sleeve bearings:
http://www.papst.de/pdf_dat_e/S17gb.pdf

There are decent fans that use sleeve bearings like Pabst and Panaflo,
but it is true that often a sleeve bearing is a sign of a cheap/junk
fan. Pabst and Panaflo fans have pretty good bearings that'll last
near as long at room temps, in a vertical mounting position, but even
so an equivalent quality dual-ball-bearing fan will last a lot longer
in high-heat environments. The main thing is to lube the
sleeve-bearing before it dries out and starts grinding into dust,
getting noisey.

Dave

kony wrote:

My Turbo2 also had only the tiny 'sink, but since it sits on the board
at a somewhat 45 degree angle, it allowed a few slow 60mm fan to be
mounted diagonally across half of a traditional 40-50mm 'sink... half
the reason I changed the 'sink was so I had a nice location to mount
the fan for cooling the voltage regulator/capacitor area to the left.
I was using a relatively low-CFM CPU heatsink fan so a bit of extra,
directed airflow did seem to help.

Hmmm, I just realized something, I've been getting my MSI motherboad's
names mixed-up... I was thinking of a K7T266 Pro2 half the time, and
the other half I was thinking about a K7T Turbo2 (I've had both). The
Turbo2 already had heatsinks on the voltage regulators from the
factory, and was unusual in that it used a 12V P4 connector for CPU
power. What I previously described about "draping a fan" to cool the
reguloators/caps, was on the K7T266 board. On the K7TTurbo2 I cooled
the northbridge passively, used 1/3 of an old P2 Katmai heatsink, cut
off.. was one of those OEM-passive-type with really tall tines. It
must've done well enough, I recally that the board was stable over
150MHz FSB, around which point the USB ports crapped out.

I remember Katmai as a P3 core, but never mind that...

You know, by looking at my board, it looks like it was designed to have have
the really hot parts be cooled by CPU-fan airflow. The northbridge, voltage
regulators and caps which get hot, are all located around the socket. As
you know, I don't have a CPU fan anymore, and some of the parts get very
hot. I told you yesterday that I have two caps which get a bit warmer than
the rest, but I tried again today and they actually get very very hot. I
burn my finger on them. My alcohol-thermometer says they're 52 degrees C. I
don't think a stronger airflow from a PSU fan is going to fix this. I think
I need a fan blowing over the parts. I tried this with my desk-fan and then
the caps are hardly hot at all.

Perhaps you could explain something to my BTW. On the caps is written "SM105
degrees C" (but with a degree sign). Does that mean that they're capable of
running stably at 105 degrees C?

I do recall some people reporting that a couple of caps right above
the AGP slot were prone to failure, the one in the middle and the
other next to the memory slots, right below the northbridge.

The caps on my board which get so hot are at the top-edge of the board (in
tower mount), above the CPU.

Here's a Pabst spec sheet that seems to indicate sleeve bearings:
http://www.papst.de/pdf_dat_e/S17gb.pdf

There's only one 12 db fan, and it uses a sleeve, so I guess my fan uses a
sleeve

There are decent fans that use sleeve bearings like Pabst and Panaflo,
but it is true that often a sleeve bearing is a sign of a cheap/junk
fan. Pabst and Panaflo fans have pretty good bearings that'll last
near as long at room temps, in a vertical mounting position, but even
so an equivalent quality dual-ball-bearing fan will last a lot longer
in high-heat environments. The main thing is to lube the
sleeve-bearing before it dries out and starts grinding into dust,
getting noisey.

Are the fanblades removable? I mean, how else can I grease it up when the
fanblades can't be removed.

BTW. I noticed that when I open my cdrom drive, hot air is coming out of it.
I seems that the excess pressure inside the case can't flow out through the
PSU. This confirms a bit that my PSU is too full of components. But on the
other hand, the back of my computer has airholes in it, though which
pressure can escape. Any thoughts on this?

Halfgaar
--
To send email, change nospam.com into yahoo.com.

On Fri, 27 Jun 2003 00:20:29 +0200, Halfgaar
wrote:

Perhaps you could explain something to my BTW. On the caps is
written "SM105 degrees C" (but with a degree sign). Does that
mean that they're capable of running stably at 105 degrees C?

Yes, within 2000 hours :-(

On Fri, 27 Jun 2003 00:09:59 GMT, kony wrote:

It's an exhaust fan, right? The sticker you need to peel back should
already be facing the outside of the system, so you don't even need to
open the case (unless your PSU still has a fan grill on it... if it
does, i'd remove/cut-out that grill. Just peel the sticker back, then
there may be a rubber or plastic plug, which when removed exposes the
fan shaft... just a drop or two of oil, the thicker the better (will
also reduce it leaking back out if the plug doesn't make a perfect
seal). Synthetic gear-oil is good, grease mixed with motor oil is ok
too, but avoid light oils or non-lubricants like WD-40.

Images.

http://w1.857.telia.com/~u85710476/d...mple/fan01.jpg

http://w1.857.telia.com/~u85710476/d...mple/fan02.jpg

kony wrote:

People who use cheap heatsinks which compensate for lack of metal with
a few high-flow fan have it better in this regard, there's more,
cooler air coming off the 'sink, while I always use highly efficent
large 'sinks with low-flow fans, so there's less but hotter air. For
me a 50-60mm fan running at 7V helps keep that area cooler than any
other method, with negligable noise.

There are other "hard-core" methods of keeping the caps cooler, but
most aren't worth the effort... for example if the board has vacant
spots for more caps in parallel, adding those caps would decrease the
ripple current, and the ESR as a whole is lower, with the heat
generated being spread among more caps. Another option is replacement
with lower ESR caps, either larger in the similar low-ESR Aluminum
variety, or something like an organic cap.

Yes, but not really... They can function properly up to that temp,
without being rapidly destoyed, but will have a decreasing, very short
lifespan. Think of capactiors like incandescent light-bulbs, in that
they wear out and need replaced on a regular interval... what that
interval is in an otherwise-static environment, depends on how hot
they run, and how much the circuit is over-engineered, so that even if
the cap is below it's acceptable value after a period of time, it
still functions enough for the circuit it's in.

Ken said about 2000 hours, which is not very much... My two year old HD has
already 7000 hours on it, according to SMART.


Sounds like you need a fan ;-)

[...]


It's an exhaust fan, right? The sticker you need to peel back should
already be facing the outside of the system, so you don't even need to
open the case (unless your PSU still has a fan grill on it... if it
does, i'd remove/cut-out that grill. Just peel the sticker back, then
there may be a rubber or plastic plug, which when removed exposes the
fan shaft... just a drop or two of oil, the thicker the better (will
also reduce it leaking back out if the plug doesn't make a perfect
seal). Synthetic gear-oil is good, grease mixed with motor oil is ok
too, but avoid light oils or non-lubricants like WD-40.


When the interior is pressurized air will escape any and everywhere it
can. That's actually a good thing, provided there's enough airflow.
With the power supply's rear exhaust hole cut out and another hole in
the "rear" of the PSU (towards the front of the case) or under the
PSU, and a second fan added to this location, the density of the PSU
interior shouldn't be so great as to impede proper airflow... after
all, in theory they designed it to stay cool enough with proper
airflow rate. I'd rather have a full power supply than one with a lot
of extra space in it, a higher-wattage PSU with good electrical
properties will indeed leave little extra space inside a standard PS2
sized PSU casing. Considering your motherboard capacitor temps, I'd
either replace the PSU with one having a fan underneith, or cut out a
fan hole, stategically placing the fan (and additional ductwork if
necessary) to move some air past that region of the motherboard).
Adding a fan may only work if you have at least 11mm of clearance
between the motherboard and PSU, for a 10mm thick fan, though
certainly as thick a fan as possible would be preferrible, greater
CFM/noise ratio.


Dave

I don't even have the fangrill cut out, that's a good idea. It probably
decreases turbulence as well, won't it? When I'm at it, I'll also cut a
hole for an 80mm intake fan. I have enough space for a fan on the outside
of the PSU (inside of the computer), the PSU is mounted on it's side next
to the mainboard, not above it. Perhaps the hole itself and the removed
fangrill will help enough, but I don't think so. I just hope there is room
for the hole for the intake fan. There are parts mounted on every side of
the PSU on the inside.

BTW, are those 12 to 7 volt adapters widely available?

On Sat, 28 Jun 2003 00:58:09 +0200, Halfgaar
wrote:


Yes, but not really... They can function properly up to that temp,
without being rapidly destoyed, but will have a decreasing, very short
lifespan. Think of capactiors like incandescent light-bulbs, in that
they wear out and need replaced on a regular interval... what that
interval is in an otherwise-static environment, depends on how hot
they run, and how much the circuit is over-engineered, so that even if
the cap is below it's acceptable value after a period of time, it
still functions enough for the circuit it's in.

Ken said about 2000 hours, which is not very much... My two year old HD has
already 7000 hours on it, according to SMART.

True, the lifespan is short, but hopefully the board is overengineered
enough that it's lifespan exceeds it's useful life. I always "try" to
keep temps low enough that I can leave my finger on the cap
indefinitely.


I don't even have the fangrill cut out, that's a good idea. It probably
decreases turbulence as well, won't it?

Yes, and increases airflow. If it's a stamped-in fan grill, removing
it alone may greatly increase the airflow.

When I'm at it, I'll also cut a
hole for an 80mm intake fan. I have enough space for a fan on the outside
of the PSU (inside of the computer), the PSU is mounted on it's side next
to the mainboard, not above it. Perhaps the hole itself and the removed
fangrill will help enough, but I don't think so.

Don't cut a hole underneith unless you're committed to installing a
fan there... otherwise, the rear portion of the PSU will receive even
LESS airflow. COnsidering that you still had the fan grill on the
rear I'd expect that adding a second 12db Pabst fan will be enough,
but with the PSU in that location it does little to help cool the
motherboard.

I just hope there is room
for the hole for the intake fan. There are parts mounted on every side of
the PSU on the inside.

What brand of PSU is it again?
Since your PSU is mouted in front of the mobo, you may or may not have
room for mounting a fan on the outside of the PSU casing... might
depend a lot on the configuration of the water-cooling block but I'd
expect it to be more accomodating than a large traditional heatsink.

BTW, are those 12 to 7 volt adapters widely available?

No, there may be some places that sell them ready-made for a premium
price, but IMHO, the best thing to do is find the lowest price in your
region for a regular 4-pin-to-3-pin adapter, then just swap the wires
in the connectors, the ground for the fan with the 5V wire (just be
sure to swap both ends, to minimized the risk of frying something
later attached to the adapter, be sure you have the right voltages on
the right pins at each end-connector of the adapter. Here's an
example of the adapter I mean:

http://www.svcompucycle.com/3pinto4pinad.html


Dave

On Fri, 27 Jun 2003 23:30:01 GMT, kony wrote:

I don't even have the fangrill cut out, that's a good idea.
It probably decreases turbulence as well, won't it?

Yes, and increases airflow. If it's a stamped-in fan grill,
removing it alone may greatly increase the airflow.

And put the noise down!

On Sat, 28 Jun 2003 18:55:39 GMT, kony wrote:

I would trust the case manufacturer's design TOO much.. after all, in
a traditional mid-tower case with PSU above the mobo, there's still
good reason to have a fan behind the CPU on the rear case wall, and
both Intel & AMD as well as most of the OEMs promote this design too.
I can't really speculate about how low the temps will be, it's a
unique system in a sub0optimal case and there's the ambient temps to
consider too. You'll just have to try a few things and see the
results.

My case is an example, I made a modification to put in another fan
in the rear och now it's 3 fans (inluding PSU fan) and two fans
in the bottom front to cool the HDD:s
http://w1.857.telia.com/~u85710476/docs/pcny51se.html
(My PC building project is not completed yet)