Is it OK to plug two 120mm case fans to the MB headers?

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DaisyHead

Member
Aug 16, 2003
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Still in the planning phase: two 120mm fans in an Antec SLK3700 plugged into the NF7-S mobo headers. Is that advisable?
 
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THUGSROOK

Elite Member
Feb 3, 2001
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Originally posted by: DaisyHead
Still in the planning phase: two 120mm fans in an Antec SLK3700 plugged into the NF7-S mobo headers. Is that advisable?
Click to expand...

no
 
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optimistic

Diamond Member
Apr 29, 2001
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Originally posted by: DaisyHead
Still in the planning phase: two 120mm fans in an Antec SLK3700 plugged into the NF7-S mobo headers. Is that advisable?
Click to expand...

I read somewhere it's not advisable. It draws too much power. 80mm or 92mm is the cutoff point.
 
SithSolo1

SithSolo1

Diamond Member
Mar 19, 2001
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I'd say 80 is the cut off, but I personally wouldn't run anything over a 60 on the mobo headers.
 
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Gravity

Diamond Member
Mar 21, 2003
5,685
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Um, K!

I harvested two 120mm sunons from an old dell server and put one on my slk900a. It's been running for about 4 months that way on a gigabyte ga-7vaxp ultra. Should I back it down to a 92?
 
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tallman45

Golden Member
May 27, 2003
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If your SLK3700 (BQE does, AMB does not) has "fan only" connectors then that would be the best solution.
 
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sugarkang

Senior member
Nov 16, 2003
248
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what does fan header mean? the 3pin connector for a fan on the mobo?

and if so, then shoot. i've got ONE 120mm fan connected to a molex to 3pin adapter, which is then connected to a zalman fanmate, which is then connected to the mobo.

120mm fan --> molex to 3pin adapter --> zalman fan mate --> mobo

just one fan. is this okay? i have the fan turned way down.
 
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andypress

Member
Jan 7, 2004
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This would probaly be the easiest and quickest way to kill your motherboard. My TT Smart Fan II cam with an adapter, and the only reason why it had a 3 pin was so you could monitor voltages. And that was an 80mm fan.
 
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InlineFive

Diamond Member
Sep 20, 2003
9,599
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The Fan Only connectors on Antec power supplies are special channels which undervolt fans (typically 5v) but raises it to full speed (12v) if the system temperature rises too high. This lowers noise but will also lower airflow.

Cheers!

-Por
 
Wuzup101

Wuzup101

Platinum Member
Feb 20, 2002
2,334
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As stated above the real problem is the amount of current that the fan draws. In general it takes more juice to start and then operate a larger fan because the motor tends to be larger (driving bigger blades). To be short, I wouldn't really suggest plugging a 120 into the mobo; however, I have seen it done without a problem. It also depends on the fan itself. If it's very low output it (with a slow motor) it probably is safe. I'm sure a 60watt delta draws more current than some low output 120s on the market. However, if you don't want to risk it, it's not a big deal to adapt it to run off of a normal molex. If you have some acceptable wire and know how to make molex plugs just go that rout... if not get an adapter(s). They are cheap so it's not worth risking mobo problems down the road.
 
myocardia

myocardia

Diamond Member
Jun 21, 2003
9,291
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Originally posted by: tallman45
If your SLK3700 (BQE does, AMB does not) has "fan only" connectors then that would be the best solution.
Click to expand...
My AMB does.
 
myocardia

myocardia

Diamond Member
Jun 21, 2003
9,291
30
91
Daisy, most 120mm fans have a 4-pin connector, not a 3-pin anyway. The Antec 120mm fan that I bought for my SLK-3700 came with a 4-pin connector, to power the fan, and a 3-pin sensor-only connector. That seems to me the perfect way to run a fan that large, especially since I don't like changing motherboards that much!

edit: The SLK-3700 comes with one 120mm exhaust fan, and it has a 4-pin connector only.
 
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sugarkang

Senior member
Nov 16, 2003
248
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well if i've got a zalman fanmate on my 120mm, but i have it all the way turned down, am i actually drawing less volts from the mobo? or is it the same amount of voltage either way, fanmate or not?

edit: i have an ADDA 120mm 12volt 0.24a
i heard that anything under 0.3a should be ok. can someone verify?
 
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redivider

Member
Dec 18, 2003
35
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0
Originally posted by: PorBleemo
The Fan Only connectors on Antec power supplies are special channels which undervolt fans (typically 5v) but raises it to full speed (12v) if the system temperature rises too high. This lowers noise but will also lower airflow.

Cheers!

-Por
Click to expand...

Do you know where I can find more info about this? I have two 120mm fans connected to the Fan Only connectors on an Antec 430w PSU and I'm trying to figure out why they never seem to speed up. I guess the temp isn't getting high enough, but I'd like to at least know what going on with it.
 
M

Mday

Lifer
Oct 14, 1999
18,647
1
81
Originally posted by: Wuzup101
As stated above the real problem is the amount of current that the fan draws. In general it takes more juice to start and then operate a larger fan because the motor tends to be larger (driving bigger blades). To be short, I wouldn't really suggest plugging a 120 into the mobo; however, I have seen it done without a problem. It also depends on the fan itself. If it's very low output it (with a slow motor) it probably is safe. I'm sure a 60watt delta draws more current than some low output 120s on the market. However, if you don't want to risk it, it's not a big deal to adapt it to run off of a normal molex. If you have some acceptable wire and know how to make molex plugs just go that rout... if not get an adapter(s). They are cheap so it's not worth risking mobo problems down the road.
Click to expand...

unfortunately, no one stated it above. it's NOT the voltage (which was repeated before Wuzup's post). it's the current draw. contact the manufacturer or read your manual as to how much current each header can output. then find a fan that draws less current than that. size doesnt matter, as long as the fan does not draw more current than the header can output without killing itself. a 60W delta would draw 5 amps, since the headers operate at 12 VDC. this IS A LOT OF CURRENT for the fan header.
 
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