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PSU Fans
Hey all.
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. Thanks. Martin. |
#2
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"Muttly" wrote in message ... Hey all. My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence that's not going to be very good... install it the other way around between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. Thanks. Martin. |
#3
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"Muttly" said in :
Hey all. My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. Thanks. Martin. The fans must provide airflow in the *same* direction through the power supply. Think about it: if you put 2 fans against each other but they were blowing against each other (one blows at the other which blows back, or they both try to suck away from each other), you get very little airflow (and instead just get turbulence) unless the airflow for one fan is much higher than the other and can overpower it. The fan on the backside of the power supply should be blowing outward (i.e., from inside the power supply to the outside). The bottom fan should be blowing into the power supply. That way the two fans are pulling or blowing air through the power supply in the same direction (disregarding the bend of the airflow from bottom to side). From your description, is the bottom fan (which should be blowing upward and into the power supply) actually on the *outside* of the power supply? It is likely the power supply's case consume the standard volume as spec'ed for an ATX power supply. That means the bottom fan being on the outside of the power supply is extending beyond the volume set aside for the power supply and intruding into the volume that would be assume usable by the motherboard and any components sitting atop it. -- __________________________________________________ __________ *** Post replies to newsgroup. E-mail is not accepted. *** __________________________________________________ __________ |
#4
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"*Vanguard*" wrote in message ... "Muttly" said in : The fans must provide airflow in the *same* direction through the power supply. Think about it: if you put 2 fans against each other but they were blowing against each other (one blows at the other which blows back, or they both try to suck away from each other), you get very little airflow (and instead just get turbulence) unless the airflow for one fan is much higher than the other and can overpower it. The fan on the backside of the power supply should be blowing outward (i.e., from inside the power supply to the outside). The bottom fan should be blowing into the power supply. That way the two fans are pulling or blowing air through the power supply in the same direction (disregarding the bend of the airflow from bottom to side). From your description, is the bottom fan (which should be blowing upward and into the power supply) actually on the *outside* of the power supply? It is likely the power supply's case consume the standard volume as spec'ed for an ATX power supply. That means the bottom fan being on the outside of the power supply is extending beyond the volume set aside for the power supply and intruding into the volume that would be assume usable by the motherboard and any components sitting atop it. SAY WHAT?? What you been smokin? Muttly, mount the friggin PSU like its supposed to be with the fan pointed down. It aint nuclear science like some would like to make you believe. Hank |
#5
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"Hank" said in .com:
"*Vanguard*" wrote in message ... "Muttly" said in : The fans must provide airflow in the *same* direction through the power supply. Think about it: if you put 2 fans against each other but they were blowing against each other (one blows at the other which blows back, or they both try to suck away from each other), you get very little airflow (and instead just get turbulence) unless the airflow for one fan is much higher than the other and can overpower it. The fan on the backside of the power supply should be blowing outward (i.e., from inside the power supply to the outside). The bottom fan should be blowing into the power supply. That way the two fans are pulling or blowing air through the power supply in the same direction (disregarding the bend of the airflow from bottom to side). From your description, is the bottom fan (which should be blowing upward and into the power supply) actually on the *outside* of the power supply? It is likely the power supply's case consume the standard volume as spec'ed for an ATX power supply. That means the bottom fan being on the outside of the power supply is extending beyond the volume set aside for the power supply and intruding into the volume that would be assume usable by the motherboard and any components sitting atop it. SAY WHAT?? What you been smokin? Muttly, mount the friggin PSU like its supposed to be with the fan pointed down. It aint nuclear science like some would like to make you believe. Hank It all depends on which ATX specification the power supply follows. In ATX pre-2.2 power supplies, the air flow was INTO the case at the rear panel so air flow was INTO the power supply's opening on the backside of the case; i.e., the power supply's rear opening was an air inlet. This contradicted the earlier AT spec which had air flow move out of the case as an exhaust port. ATX 2.2 reversed the air flow and now, like the AT spec, has airflow move OUT of the power supply at the rear panel. So for the power supply opening at the rear of the case: - For an AT power supply, air flow is OUT of the case. - For an ATX pre-2.2 power supply, preferred air flow is INTO the case. - For an ATX 2.2 power supply, preferred air flow is OUT of the case. ATX 2.01 Specification (released 1996), Section 4 ftp://download.intel.com/design/motherbd/atx_201.pdf ATX 2.03 Specification (released 1997), Section 4 http://ulita.ms.mff.cuni.cz/pub/techdoc/atx/atx2_03.pdf "The 'preferred' airflow solution is to pull air through the power supply from outside the chassis and direct it onto the processor. However, other solutions may be implemented to meet the specific cooling requirements." ATX 2.1 Specification http://www.formfactors.org/developer...s%5Catx2_1.pdf This spec doesn't say anything about airflow direction for the power supply. There is the implication that airflow is the same as in the prior specs per Section 5.1, "Venting", where it says, "Adequate venting should be provided in the system to allow for unimpeded and well-designed airflow to cool key components such as the processor." But airflow in either direction across the processor would assist removal of the warmed air from the processor (although a PSU that exhausts air across the processor may be doing so with pre-warmed air taken into the PSU through its internal-side vents). ATX12V 2.2 Specification, Section 4.3 http://www.formfactors.org/developer...20Ratified.pdf "In general, exhausting air from the system chassis enclosure via a power supply fan at the rear panel is the preferred, most common, and most widely applicable system-level airflow solution." The ATX specification as regards to the direction of airflow through the power supply are only recommendations (i.e., they are ambiguous). As such, you have to test your power supply to see which direction is its airflow. I picked up a Fortron 350W PSU about 2 months ago which has 2 fans. The bottom fan is an inlet port (air goes INTO the power supply) and the rear fan is an exhaust port (air goes OUT of the power supply). So my power supply is ATX12V 2.2 compliant, and the fans work in concert to pass air *through* the power supply instead of working against each other. The bottom fan is primarily a backup in case the rear fan stops spinning or spins too slowly (especially for rear fans with manual speed adjust). Sometimes the rear fan is temperature controlled but the bottom fan is usually fixed speed (because it is the backup or to ensure a minimal flow rate). 2 equally strong guys push against opposite sides of a crate. The crate doesn't move. The same 2 equally strong guys pull against opposite sides of a crate. The crate still doesn't move. 2 guys of different strengths push against opposite sides of a crate. The crate moves slowly in the direction of the weaker guy. 2 guys of different strengths pull against opposite sides of a crate. The crate move slowly in the direction of the stronger guy. 2 guys of equal or unequal strength either both push or pull against the crate in the same direction. The crate moves fastest in that direction because the guys work together instead of opposing each other. Fans provide the force. Air has mass and momentum, too. Hank never took physics in high school, or he failed, or he skipped that class or high school altogether. If the ATX power supply has the *optional* cooling vents on the inside (where the wire harness exits), the fans could both be pushing air out of the power supply; i.e., the rear fan would exhaust out of the case and the bottom fan would exhaust out across the processor. That is because you now have an alternate path for airflow other than through the openings for the fans. However, realize that the vent openings on the internal side of the power supply are rarely sufficient in their cumulative size to accomodate the same [potential] airflow provided by just one of the fans. Also realize that the bottom fan would then be recirculating the pre-warmed air from inside the case across the processor. So despite if there are vents or not, you want to either move the cold air in or the warmed out. You don't want to be sucking the air that has already been warmed by the hard drives, expansion cards, RAM sticks, and processor into the power supply's inlet vents to only then get recirculate that pre-warmed air back over the processor. Your CPU probably has its own fan. Figure out which way the rear fan in the power supply is directing airflow, then make the bottom fan on the power supply move the air in the same direction so it assists with airflow rather than opposes it. -- __________________________________________________ __________ *** Post replies to newsgroup. E-mail is not accepted. *** __________________________________________________ __________ |
#6
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The thing that made me question you drug habits is that after the OP clearly
states that both fans are internal to the PSU you came up with this gibberish. From your description, is the bottom fan (which should be blowing upward and into the power supply) actually on the *outside* of the power supply? It is likely the power supply's case consume the standard volume as spec'ed for an ATX power supply. That means the bottom fan being on the outside of the power supply is extending beyond the volume set aside for the power supply and intruding into the volume that would be assume usable by the motherboard and any components sitting atop it. Hank |
#7
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"Hank" said in .com:
The thing that made me question you drug habits is that after the OP clearly states that both fans are internal to the PSU you came up with this gibberish. From your description, is the bottom fan (which should be blowing upward and into the power supply) actually on the *outside* of the power supply? It is likely the power supply's case consume the standard volume as spec'ed for an ATX power supply. That means the bottom fan being on the outside of the power supply is extending beyond the volume set aside for the power supply and intruding into the volume that would be assume usable by the motherboard and any components sitting atop it. Hank Hey, some of us get interrupted while we are working even if it is at home. I forgot or missed that he said the fans were *internal* and remembered only that he mentioned one fan was mounted on the bottom of the PSU. I thought it strange and had never seen a fan on the bottom that was outside the case but figured maybe the OP was installing the fan themself. You see some very strange stuff when folks do case mods. -- __________________________________________________ __________ *** Post replies to newsgroup. E-mail is not accepted. *** __________________________________________________ __________ |
#8
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On Wed, 11 Feb 2004 01:02:53 -0000, "Muttly" wrote:
Hey all. My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. Thanks. Martin. The fan should be facing down, blowing up, into the power supply. This results in more air movement across the middle, more of the upper left portion of the motherboard where heat-producing components like the CPU, northbridge, and power regulation circuitry are located. There is no need to move any air in-between the top of the power supply and the top of the case, since there isn't anything there that produces heat. There are exceptions, full tower cases that have hard drives mounted above the power supply, but such cases have air vents or more fan mounts above the power supply too, so the 2nd power supply fan should still be facing downwards. |
#9
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Muttly wrote:
Hey all. My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. Thanks. Fan facing down. If you look you'll see that one of the PSU mounting screws is off-set from the others. Let that be your guide. -- ~misfit~ |
#10
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"Muttly" wrote:
My PSU (I can't remember the make or model, but its 550w) has 2 fans. 1 points of the case, the other is inside the case pointing either up or down, both fans are internal to the psu. My questions is which way should I have the inside fan pointing? If it points up its got bout 4cm clearence between it and the top of the case. If it points down its right over my cpu. For better cooling which way do you think it should be pointing? If theres a site or something that will give a good reason as to which way, a link would be great. Better yet if someone has experience as to which way is best that'd be great 2. The inside fan should be on the bottom of the power supply, sucking air into the PSU. See the following webpage, http://www.highpowersupply.com/produ...0102df.htm#2nd , and click on "Close-Up Pictures" and "Function of 2nd Fan". It clearly shows that the bottom fan sucks air *into* the PSU, away from the CPU heatsink, and the end fan blows air out of the PSU and out of the case. Presumably, the airflow capacity of the end fan is greater than that of the bottom fan so that air is drawn in at the other end of the PSU, away from the optical drives and through the PSU to the exterior of the case. *TimDaniels* |
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