Another stupid fan question

[Lopaka]

I have a big antec case with a mount for a fan on the clear
plastic side cover. The case manual doesn't say wether a
fan mounted here should blow IN or OUT? Also, should
I block this vent if no fan is mounted?

Currently have 2 on the pwr supply & 2 on the back
blowing out, and none in the front.

Thanks, Rob

A7N8X DLX rev.2 Bios 1006
Win98SE (from my old HP computer)
Athlon 2600+
Mitsumi and Sony floppy drives

 

[mdp]

When the only two fans I have in a case are the one in the Power Supply and
one on the side, I install the side fan as an intake fan (blow IN) since the
PS is an exhaust fan (blow OUT). This forces circulation and I've found
through experimenting it results in slightly lower temps.

 

[Ron]

Hmm. I would first suggest that you determine your temps...before getting
too concerned about this issue. (You may discover that you do not require
additional air movement at all.) MBM5 is ideal for this.

That said, you can certainly leave the blowhole un-occupied...or pop a fan
in there. You will want to spend a couple of dollars extra to get a QUIET
fan, since it is right there at the side of the case. In the event that you
opt to install such a fan, I'd say that blowing IN is preferable. The
theory here is that you are directing air at the CPU, so obviously air
*outside the box will be cooler than air *inside the box.

Please post a follow-up.
Ron

 

[peter]

If you go to the AMD website and look at the PC Builder specs for fan
location and air circulation in any case,you will note that they suggest a
front low blow in case fan .This fan blows in cooler air whereas the rear
mounted fans should be placed higher(hot air rises)to expell the hot air.The
side cover fan usually is located in such a manner that it blows cool
outside air over the PCI cards or towards the CPU cooler.If it is on the
opposite side of the MOBO then it would be set up to draw the air out.
peter

 

[Lopaka]

Wow, thanks for the quick replies folks!
MBM5 reports 82F for MB, 32F for CPUdiode, and 109-113F for CPU (82 and 116F
in BIOS)
Room temp is 82F

If I bought 2 26db fans (one for side and one for bottom front) would they
be very noisy?

I am reading where the cha_fan connector will only support up to 350ma(4.2
watts), correct?
Or do they mean all 3 connectors (cpu,pwr,cha) support a TOTAL of 4.2 watts?
page 28.

Thanks again, Rob

 

[Rob Stow]

If you go to the AMD website and look at the PC Builder specs for fan
location and air circulation in any case,you will note that they suggest a
front low blow in case fan .This fan blows in cooler air whereas the rear
mounted fans should be placed higher(hot air rises)to expell the hot air.The
side cover fan usually is located in such a manner that it blows cool
outside air over the PCI cards or towards the CPU cooler.If it is on the
opposite side of the MOBO then it would be set up to draw the air out.
peter

Note also that if all of your fans are blowing *out* and the
only air intake if what leaks in through the case, then you
reduce the air pressure inside the case. The lower air
pressure means a lower air density - and the ability of the
air to remove heat from your heatsinks should be proportional
to the density.

I have seen computer cases where all of fans are blowing
outward and there are no big vents to let air flow into
the case: plastic side panels on a case can bulge inward
very noticeably when the system is powered up - which clearly
indicates a reduction of air pressure inside the case.
Even on steel cases you can detect side panel concavity by
taping small mirrors to the panels and noting the changes
in the angle at which the beam from a laser pointer is
reflected.

Turning even just one fan around so that it blows inward can
give you a dramatic temperature reduction and a noticeable
noise reduction.

On a system with a PSU fan and three case fans I have found
that I get the best temperatures when two case fans blow
inward and only the highest case fan blows outward. When
there is only one case fan, I always get the best temperatures
when the case fan blows inward and only the PSU fan blows outward.

When there are two case fans it is not so clear - sometimes it
works best when the lowest one blow in and the highest one blows
out, but other times it works best if both blow in and only the
PSU fan blows out.

My tests were all pretty crude - just three mid-tower cases and
one full tower case all with three case fans each. I simulated
one and two fan configurations by unplugging fans and using pieces
of duct tape over the grills to seal off the openings. Its been
a year and a half since then and CPUs and video cards have
gotten a *lot* hotter in the meantime - I would love to see
up to date results if someone does some tests with modern
hardware. I also did not have tools to measure air pressures
inside the case - I would have loved to be able to see various
air pressure vs temperature graphs.

 

[Ron]

Well, again...do one OR the other. Not both. I'd do the front case fan
first, and re-check temps. (The power draw ratings are *per header, not
cumulative)

Also keep in mind that, if there is negative pressure in the case, air will
naturally enter through any existing opening(s). This unfortunately means
that, in many people's cases, the optical drives double as air filters. Not
desireable.

Back to you.
Ron

 

[Lopaka]

Well, again...do one OR the other. Not both. I'd do the front case fan
first, and re-check temps. (The power draw ratings are *per header, not
cumulative)

Also keep in mind that, if there is negative pressure in the case, air will
naturally enter through any existing opening(s). This unfortunately means
that, in many people's cases, the optical drives double as air filters. Not
desireable.

Ok, sounds good, I suppose its OK to use a quiet low power fan in the
front?
Or, would that also generate too much negative pressure? IOW, would the
3750 rpm
fans in the back drag on a 2200 rpm fan in the front? (Also has an air
filter there.)

Thanks for your time and assistance.

Robert

 

[DaveW]

The side fan is designed to blow outside cold air IN onto the video card
area.

 

[Ron]

Well, I'm not exactly sure what you propose to go out and purchase. (My
plan being to save you buying anything [more] that you may not need)

Honestly? I would move one rear case fan to the front, and disconnect the
other one. Then, (with blowhole sealed off), run for awhile & re-check your
temps. Then re-connect the rear case fan, [again run for awhile] and check
temps again. I think you'll find that you don't need to buy any
*additional* fans...although you may choose to *replace* one (likely the
front) with a quieter model. In any case, try this and come back. OK?

Ron

 

[Gernot Saborowski]

I have a big antec case with a mount for a fan on the clear
plastic side cover. The case manual doesn't say wether a
fan mounted here should blow IN or OUT? Also, should
I block this vent if no fan is mounted?

Currently have 2 on the pwr supply & 2 on the back
blowing out, and none in the front.

Rob (and all others),

I made a time consuming experiment for finding the best positions for
the additional fans.

Here is the result (all values after using standard applications like
Mozilla, Defrag, OpenOffice etc, no benchmarks or games with high CPU
load; room temperature at about 21°C):
Without additional fan:
CPU 52°C
MB 37°C
CPU fan: 2400 rpm

2 add. fans @ 2700rpm:
1 mounted in the side mount, bottom, air in
1 mounted front, upper mounting slot, air in
CPU 51°C
MB 29°C
CPU fan: 2250 rpm

2 add. fans @ 2700rpm:
1 mounted in the side mount, upper mount, air in
1 mounted front, upper mounting slot, air in
CPU 49°C
MB 33°C
CPU fan: 2000 rpm

2 add. fans @ 2700rpm:
1 mounted in the rear, upper mount, air out
1 mounted front, upper mounting slot, air in
CPU 45°C
MB 29°C
CPU fan: 1700 rpm

2 add. fans @ 2000rpm:
1 mounted in the rear, upper mount, air out
1 mounted in the rear, bottom, air out
CPU 42°C
MB 24°C
CPU fan: 1400 rpm

Conclusion:
If there are enough inlets for cool air, the best is to get the hot air
out of the case fastest. I have set the add. fans to minimum speed for
getting rid of the noise. My computer is a lot more quite with the two
add. fans because they effect that both the CPU fan and the fan in the
PSU run a lot slower. The only fan that causes the rest of the noise is
the noisy fan on my Matrox Parhelia...

System specs:
Asus A7N8X Deluxe BIOS 1007
Athlon XP2500+
Zalman ATX ZM400A-APF 400 Watt PSU
CaseTek 1019 Aluminium-Tower with noise absorber kit installed
1 GB PC 3200 DDR-RAM
Matrox Parhelia 128, DualHead setup


HTH, best regards,

-Gernot

 

[Rob Stow]

Rob (and all others),

I made a time consuming experiment for finding the best positions for
the additional fans.

Here is the result (all values after using standard applications like
Mozilla, Defrag, OpenOffice etc, no benchmarks or games with high CPU
load; room temperature at about 21°C):
Without additional fan:
CPU 52°C
MB 37°C
CPU fan: 2400 rpm

2 add. fans @ 2700rpm:
1 mounted in the side mount, bottom, air in
1 mounted front, upper mounting slot, air in
CPU 51°C
MB 29°C
CPU fan: 2250 rpm

2 add. fans @ 2700rpm:
1 mounted in the side mount, upper mount, air in
1 mounted front, upper mounting slot, air in
CPU 49°C
MB 33°C
CPU fan: 2000 rpm

2 add. fans @ 2700rpm:
1 mounted in the rear, upper mount, air out
1 mounted front, upper mounting slot, air in
CPU 45°C
MB 29°C
CPU fan: 1700 rpm

2 add. fans @ 2000rpm:
1 mounted in the rear, upper mount, air out
1 mounted in the rear, bottom, air out
CPU 42°C
MB 24°C
CPU fan: 1400 rpm

Conclusion:
If there are enough inlets for cool air, the best is to get the hot air
out of the case fastest. I have set the add. fans to minimum speed for
getting rid of the noise. My computer is a lot more quite with the two
add. fans because they effect that both the CPU fan and the fan in the
PSU run a lot slower. The only fan that causes the rest of the noise is
the noisy fan on my Matrox Parhelia...

System specs:
Asus A7N8X Deluxe BIOS 1007
Athlon XP2500+
Zalman ATX ZM400A-APF 400 Watt PSU
CaseTek 1019 Aluminium-Tower with noise absorber kit installed
1 GB PC 3200 DDR-RAM
Matrox Parhelia 128, DualHead setup


HTH, best regards,

-Gernot

Priceless data. Sounds like in makes it well worth
drilling holes in a case to provide air inflow so that
all the fans can blow outward. The case for my home
system, for example, doesn't have any significant openings
other than the ones already used by the two case fans.

Smatter of fact, just removing one of the covers for an
unused PCI slot should make enough of a difference that
I could reverse the fan that currently blows inwards.

As for you Parhelia, is the 2D image quality as good as
I have heard ? I don't care about 3D but I do want excellent
2D quality on dual monitors. A Parhelia is out of my price
range but a G650 and maybe even a G750 should be achievable.

 

[Gernot Saborowski]

Priceless data. Sounds like in makes it well worth
drilling holes in a case to provide air inflow so that
all the fans can blow outward. The case for my home
system, for example, doesn't have any significant openings
other than the ones already used by the two case fans.

Maybe. Fortunately, my case has enough openings for air inflow (7
mounting positions for additional fans with openings for each fan...).

Smatter of fact, just removing one of the covers for an
unused PCI slot should make enough of a difference that
I could reverse the fan that currently blows inwards.

Yeah, thats's true. Opening the case is always good for the temps... But
I like it silent ;-)

As for you Parhelia, is the 2D image quality as good as
I have heard ? I don't care about 3D but I do want excellent
2D quality on dual monitors. A Parhelia is out of my price
range but a G650 and maybe even a G750 should be achievable.

I am with Matrox cards for 6 years now and I don't want another brand
card... Brilliant colors (in Matrox-language Gigabit-Color ;-) ),
ultra-sharp display with moderate 3D performance makes it very good for
me...


Regards,

-Gernot

 

[Rob Stow]

Maybe. Fortunately, my case has enough openings for air inflow (7
mounting positions for additional fans with openings for each fan...).

I gave that a try and my temps actually went up by
2'C (to 32'C) for the MB and by 4'C (to 52'C) for the cpu.
Probably because the video card and the PCI cards I have
interfere too much with the airflow coming in through the
open PCI slot. Air inflow from the lower front of the case
would probably be a lot better, but I am not prepared to start
cutting and drilling holes when my original fan configuration
(case fan below PSU blowing out, plus side panel fan in the lower
front corner blowing in) was adequate.

Yeah, thats's true. Opening the case is always good for the temps... But
I like it silent ;-)



I am with Matrox cards for 6 years now and I don't want another brand
card... Brilliant colors (in Matrox-language Gigabit-Color ;-) ),
ultra-sharp display with moderate 3D performance makes it very good for
me...

I've got an ATI Radeon 9200 collecting dust right now.
It was literally a painful step down in image quality
from the Matrox G550 I previously had, so I put the G550
back in. I was going to give the Radeon to my nephews
but their mother doesn't want them to have an upgrade
that will encourage them to play more games.

The Radeon's text/image quality initially seems poorer
than the G550 but still adequate - but I can spend
all day working with the G550 yet got nasty headaches
after just a couple of hours when I used the Radeon.

Nothing really wrong with the G550 for what I do -
except that once in a while I like to bump my monitor
resolutions up to 1600x1200 and the G550 seems to be
gasping for air at that res. Hence I am considering
a newer Matrox card.

 

[AxeClinton]

What you want to do in a case is exchange the inside air with cooler outside
air as much as possible. So the best arrangment is to pull the air, exhaust the
inside hot air out the back and assist the process by pulling ouside air into
the case through the front. In a tower case the ideal arrangement is to pull in
cool air at the bottom front, have it sweep across the mobo and up toward the
top back for extraction by the rear top fan. So set the fan to blow in at the
bottom front and out at the top back. It is also helpful to have some fans blow
at hot spots like video cards inside the case. I installed two additional fans
with extra strength Velcro to blow on internal cards and at my Hard Drive bays.

If case maunfatures made provisions for large fans instead of the samll crappie
ones they use then RPM's could be reduced with the large blades moving more
air. One large fan in the front and one in the top back moving more slowly and
quieter could do the job of two small fans in the top back whining away at high
speed..

--Nat

 

[BoB]

Here's a different story, my case has dual 80mm low front blowing in,
one 90mm high back/out, a side vent with stack adjustable to fit close to
cpu fan and draw cool air directly to heat sink. With side on this summer
it started getting above 50C for cpu, by removing the rear exhaust fan, cpu
temps went down about 3-4degreesC.
The rear exhaust fan was too strong?? pulling cool air away from the
cpu fan???

 

[gawderho]

I agree with your post, the most.

Because,

Antec's Sonata Black Case uses this method with one 120mm cooling fan
mounted in the upper rear with vibration reducing rubber grommets, and one
optional 120mm cooling fan mount in the front bottom behind the 3.5"
internal drive bays.

So I added the optional 120mm intake fan.

The drive bays are side mounted so more surface area is exposed to intaking
air, across your hard drives.

The one feature I added was a double fanned PSU to draw hot air off the CPU
and I've never had to take the sides off the case.

The BIG fans are the answer, I think.

My CPU Temp right now is 28C/82F and MB is 31C/87F on a P4P800 Deluxe P4
2.4C. Not bad huh? ..............Gawderho

 

[AxeClinton]

Great story LOL. It seems like almost everything in the PC world sucks, almost
nothing is well thought out. I have been playing with computers since before
the old Radio Shack TRS-80 and Aplle II. Electrically and mechanically I have
NEVER seen a more poorly thought out and desigened product than the PC. Simple
and obvious things escape the design of the PC and things that should be easy
to work out seem beyond them.

Effective cooling is a critical element in today's machines yet almost no
serious attention is paid to this by OEM's and case manufacturers. The
instability and overall unreliability of the PC caused by sloppy design is
deplorable.

A simple and effective way to cool off hard drives for example would be to take
a lesson from radio manufactures. In a typical VHF/UHF transmitter the cast
housing has fins molded into the design. There is basically a heat sink
designed into the housing. If Hard Drive manufacturers would copy this design
so that the back of the hard drive had fins anout 3/4" long along the width of
the drive, painted black to improve IR radiation, just some modest air flow
across the fins inside the case would effectively cool them. If you ever felt
how hot hard drives run inside the drive bay you would appreciate the need for
this. But they won't do this BECAUSE THEY NEVER DID IT! They can't even get the
power plugs in SATA right. Have you seen the lousy quality of USB connectors?
They can't come up with a standard, even with the more simple SATA connector,
so that Hard Drives can mate with connectors for power and data in the Drive
Bay so that you can simply slide a hard drive in and out of the case and key
lock it in place from the front of the case. Instead when one fails you have to
battle with it banging up against the CPU to fit it in the bay becuse the
screws to remove the bay are not accessible and they don't expect you to EVER
change a drive.

They talk about the PC being the hub of your entertainment system but don't
place headphone jacks up front.

Drives are cheap today and every machine should have a backup drive that is
contantly mirroring your primary. Loss of data is the biggest problem for
computer users, especially the non-techie who knows nothing about backing up
their machines. All drives should be hot swapple by now and in a consumer
machine when a drive fails the OS should be smart enough to switch to the
mirror, tell the consumer about the failure and indicate that the sysem is
running on the backup and advise him to go buy a new drive and just slide it in
from the front panel like a VCR tape. The system should then rebuild the files
and the system should be up and running in an hour or two WITHOUT any user
intervention. The OS and the hardware should be designed to do this. It should
NOT require a computer expert every couple of months to fix consumer's
computers.

Every computer should have a small and cheap battery back up built in just to
handle things like 30 second glitches. It would not need to be a big battery
and it need not shut the system down, just keep the mobo and drives live for up
to 30 seconds. Most power drops outs where I live are for a second or so, just
enough to crash the system. If they built 30 seconds of backup into each
machine it would effectively deal with most power glitches for the majority of
users. For more security, standard external backups can be purchased.

I am so sick of having to fix computers for friends and family members becasue
the idiots at Microsoft and all the OEMS can't or refuse to understand that the
biggest roadblock to people going out and buying PC's is not speed or money,
it's relaibility or lack of such.

Getting back to the original post. It does not take a degree in rocket science
to model air flow inside a computer case with cards and components installed.
If the industry gave a damn they would create guidlelines and set standards for
what would be acceptable design for case cooling, ie, placement of fans in the
case and vent ports. Before a case would get the 'Good House Keeping Seal Of
Approval' it would have to be tested. If a case fails to meet standards for
cooling and RF tightness then it does not get approved.

For christ sake, they could not even set the correct standard after all these
years so that when cards are pugged into the PCI slots and the MOBO is in its
normal vertical attitude in the case so that the heat producing components sit
on TOP of the card, have you noticed when you look in your case that all your
PCI cards have the components on the left side of the card which translates to
the bottom in their normal configuration? If you want to improve the convection
cooling of your PCI cards you have to stand the computer upside down. This is
NOT rocket science!

They are so in love with the God of compatibility, with the past that they
don't care if things works or not as long as they do things the way they always
did them. There is no excuse for computers to sound like Hoover Vacuum
Cleaners! If they gave a damn cooling solutions that are effective and quiet
would exist and instead of wasting all this time on crap like this we could be
wasting all our time on all the rest of the lousy PC hardware and software that
never works right.

If the PC producers would address some of the concerns of their customers
instead of kneeling at the altar of the CPU speed God perhaps they would sell
more machines. Almost everyone I speak to hates the prospect of buying a new
machine because they know that it will take them 2 or 3 years to get all the
bugs out and just about the time they have their computer running reasonably it
will start to break down becasue of the lousy hardware and design and the next
unstable OS will be introduced by Microshaft!

I am just about ready to buy an iMac.

--Nat

 

[gawderho]

Grate (great) rap-a-tap!

To sum up your words,.......it's pure nonsense that lacks common sense and
originality.......... I mean really, you are so right..........I always
shake my head when I look at my sound card with it's daughter board plugged
upside down in the PCI slot, much less the video card, where all the
components heat rises back through the components to "easy bake" the
PCB......it's ridiculus.

Have a good day, you deserve it!

gawderho

 

[Lopaka]

Installing a side case fan to blow IN,
I experienced a temp reduction maximum of 7 degrees F. for
case, Diode and cpu socket. Thanks for the advice.