# Fan amps and watts

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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC at 25 C, but my case temperature varies from 45 C to 65 C. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?

Edited by vipejc
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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?

(8.96-8.88)/8.88=0.009 or less than 1%, well within common tolerances.

No issues whatever with voltage, if the motherboard provides 12 V (usually and more likely 12.2 or 12.3 V) this value will never be increased.

The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%)

Voltage levels and current absorption are not linear when it comes to electrical motors.

Loosely, you can:

• Think at Volts as you would think at the inner area of a water pipe.
• Think at Ampere as you would think at the pressure of the water flowing through it.
• Think at Watts as the quantity (instantly or per unit of time) of water coming out of the open end of the pipe.

To get more water you increase the pressure (the diameter of the pipe remains the same), as well if instead of flowing free from an open end of the pipe you make it deliver water in a container that is in depression, more water will flow (actually the delta of pressure is increased as well)

An electrical motor will normally attempt when under heavy stress/load (and this is not the case of a fan unless you "brake" it or it gets clogged with dust or whatever) to compensate a lower level of voltage by absorbing more Amperes.

As well, there could be issues with the (very brief in time) increase of Amperes needed to spin up, but any hardware manufacturer would take this into account when rating the current a header designed to have an electric motor connected to it can provide.

I see that you were not satisfied by the replies received here :

http://www.overclock.net/t/1337574/fan-amps-and-watts

where at least you provided the make of the fan, Delta.

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.

jaclaz

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My motherboard fan headers support fans up to 0.74A or 8.88W. I want to purchase a 12 VDC fan that's operation voltage is 6.0 to 12.8 VDC. The fan has a rated current of 0.70A or 8.40W, and a starting voltage less than or equal to 6.0 VDC. Is there any chance that the fan could run at the maximum 12.8 VDC or 8.96W, exceeding my motherboard fan headers' maximum rated current and damaging the fan or motherboard?

(8.96-8.88)/8.88=0.009 or less than 1%, well within common tolerances.

No issues whatever with voltage, if the motherboard provides 12 V (usually and more likely 12.2 or 12.3 V) this value will never be increased.

The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%)

Voltage levels and current absorption are not linear when it comes to electrical motors.

Loosely, you can:

• Think at Volts as you would think at the inner area of a water pipe.
• Think at Ampere as you would think at the pressure of the water flowing through it.
• Think at Watts as the quantity (instantly or per unit of time) of water coming out of the open end of the pipe.

To get more water you increase the pressure (the diameter of the pipe remains the same), as well if instead of flowing free from an open end of the pipe you make it deliver water in a container that is in depression, more water will flow (actually the delta of pressure is increased as well)

An electrical motor will normally attempt when under heavy stress/load (and this is not the case of a fan unless you "brake" it or it gets clogged with dust or whatever) to compensate a lower level of voltage by absorbing more Amperes.

As well, there could be issues with the (very brief in time) increase of Amperes needed to spin up, but any hardware manufacturer would take this into account when rating the current a header designed to have an electric motor connected to it can provide.

I see that you were not satisfied by the replies received here :

http://www.overclock.net/t/1337574/fan-amps-and-watts

where at least you provided the make of the fan, Delta.

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.

jaclaz

Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Edited by vipejc
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Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Good , and the reason why I asked for them is because those data you provided are NOT enough for me to give you an accurate suggestion, and they sound "queer" to me.

If you prefer I would like to read myself the specs, or if you prefer even better I don't trust you on the info you posted . .

Mind you I am (was) trying to help you, it is only logical that if you cannot judge by yourself if that fan is suitable , you evidently miss some related electric/electronic knowledge , EXACTLY the same one that would allow you to decide what is necessary and what it is not.

And, as a standard, preventive disclaimer :

jaclaz

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Jaclaz, the reason I didn't share the model of Delta fan or the motherboard is because it wasn't necessary since I provided the data from both my motherboard manual and the fan datasheet. Is it safe to buy this fan, or am I cutting it too close?

Good , and the reason why I asked for them is because those data you provided are NOT enough for me to give you an accurate suggestion, and they sound "queer" to me.

If you prefer I would like to read myself the specs, or if you prefer even better I don't trust you on the info you posted . .

Mind you I am (was) trying to help you, it is only logical that if you cannot judge by yourself if that fan is suitable , you evidently miss some related electric/electronic knowledge , EXACTLY the same one that would allow you to decide what is necessary and what it is not.

And, as a standard, preventive disclaimer :

jaclaz

Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate. If you need something in specific, just ask and I'll share it.

Huh? The 12.8 is the max rated voltage of the fan, if it has a max rated consumption of 0.70 A it will consume at the most 0.70 A (+ or - some tolerance, typically 2.5 or 5%. Then 0.70A + 2.5% to 5% would put me over the cap.

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Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate.

Never said that you were telling me lies, but maybe the actual specs may contain additional info that I would like to see and that you omitted as you rated them "unnecessary".

If you need something in specific, just ask and I'll share it.

What about the EXACT Delta fan model and motherboard make/model?

You know. like :

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.

jaclaz

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Jaclaz, why would I lie about specs for my problem? I assure you all specs are 100% accurate.

Never said that you were telling me lies, but maybe the actual specs may contain additional info that I would like to see and that you omitted as you rated them "unnecessary".

If you need something in specific, just ask and I'll share it.

What about the EXACT Delta fan model and motherboard make/model?

You know. like :

Now if you would be so kind as to provide the EXACT model of the Delta fan AND the EXACT make/model of your motherboard, one could have a look at the spec sheets of both and possibly give you some more detailed advise.

jaclaz

I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.

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I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.

Where exactly did you get the data for the fan?

Unless I am mistaken, the specs are here:

http://www.delta.com.tw/product/cp/dcfans/dcfans_product.asp?pcid=1&ptid=1

AFB1212HHE -C -R00 / -F00 12 6.0 to 12.8 0.51 6.12

or here (more likely):

jaclaz

Edited by jaclaz
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I really don't see how these are required, but I'll play ball. My motherboard is an ASUS-HP A7V8X-LA Kelut GL6E and the Delta fan model is AFB1212HHE-F00.

Where exactly did you get the data for the fan?

Unless I am mistaken, the specs are here:

http://www.delta.com.tw/product/cp/dcfans/dcfans_product.asp?pcid=1&ptid=1

AFB1212HHE -C -R00 / -F00 12 6.0 to 12.8 0.51 6.12

or here (more likely):

jaclaz

I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.

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I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.

Good, this one, then:

it says that the power consumption is 0.51 A and consequently (at 12 V) 6.12 W, with a MAX of 0.70A/8.40W.

You didn't post initially this info.

That fan will normally use 0.51 A with PEAKS of 0.70 A.

Your motherboard provides (your specs that I did NOT check) 0.74A or 8.88W and provides a 12 V level.

You are well within any limits and you can safely use that fan attached to that motherboard.

jaclaz

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I got the data for the fan from the Delta datasheet called AFB1212HHE-CF00(REV00).pdf. I just double-checked the specs to make sure they're correct, and they are.

Good, this one, then:

it says that the power consumption is 0.51 A and consequently (at 12 V) 6.12 W, with a MAX of 0.70A/8.40W.

You didn't post initially this info.

That fan will normally use 0.51 A with PEAKS of 0.70 A.

Your motherboard provides (your specs that I did NOT check) 0.74A or 8.88W and provides a 12 V level.

You are well within any limits and you can safely use that fan attached to that motherboard.

jaclaz

I knew all that. The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?

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I knew all that.

But you failed to post these data.

The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?

No, what you are basically missing, and I am trying - at this point desperately - to try telling you is that if you connect a (say) 24 V device (or a 36 V or a 48 V or a 5 V or *whatever* voltage) to a 12 V outlet, the max voltage present at the outlet will remain 12 V, it is what "comes out" of the outlet and not the specs of the device attached to it.

The specific device (fan) can run continuously at 12.8 V but it is designed to be powered at 12V (i.e. it has a target of being operated at 12 V though it can accept as low as 6V and as much as 12.8V).

Power absorption is another matter, if you attach a device rated for a higher power absorption (but within the right Voltage specs) to a power outlet, the device will attempt to get more power (up to it's own specifications).

As a matter of fact when you connect a load to a voltage output, the voltage level might drop a little, but NEVER increase, if your motherboard ouputs 12V (as a matter of fact, if you had a mutimeter, you would measure on it - as said - most probably 12.2 or 12.3 V with no load connected to it and exactly 12 V or more likely 11.9 V with a "heavy" load connected) you will NEVER be able to get 12.8V from it.

Examples (simplified, and in order to let you understand) in case of BOTH an unprotected/unlimited power supply and of an unprotected/unlimited device:

Power supply specs:

12V 1A hence 12W

1. If you attach to it a device rated 6V 1A (6W) continuous, the device will burn in no time (because the voltage operating range of the device is greatly exceeded) .
2. If you attach to it a device rated 12V 1A (12W) continuous, both the device and power supply will work for years without issues (this device may well have peaks or "MAX" of up to 40% more than standard absorption - or even higher "transient" current spikes without any consequences to the device or to the power supply)
3. If you attach to it a device rated 6V 2A (12W) continuous the power supply OR the device will burn in no time.(because the voltage operating range of the device is greatly exceeded OR the current capabilities of the power supply are greatly exceeded)
4. If you attach to it a device rated 24V 1A (24W) continuous the power supply is very likely to burn (because the device will attempt to draw more current to compensate for the lower voltage)

http://en.wikipedia.org/wiki/Ohm's_law

that is the same, written differently, that gives you V x A = W (when talking of DC, NOT AC)

http://www.csgnetwork.com/ohmslaw2.html

the MAX current that device will draw is 0.70A at 12V, if you supply it with a higher voltage, let's say 12.8V it will draw LESS current, i.e.

12 x 0.70 = 12.8 x X -> X=~0.66 A

If you attach to an outlet (BTW surely protected from overcurrents) rated for 12 V 0.74A that particular fan, it will run normally at 12V (and NOT at any higher voltage) absorbing normally 0.51A with the possibility of peaks up to 0.70A.

The outlet can provide UP TO 0.74A at 12V (8.88W), the device will nornally use 0.51A at 12V (6.12W) with peaks up to 0.70A at 12V (8.40W).

You are well within the specs.

jaclaz

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I knew all that.

But you failed to post these data.

The operating voltage for this fan is 6.0V to 12.8V. My concern is is it possible that this fan could run at 12.8V and 8.96W at stock settings with no user adjustments to voltage, which is over my motherboard fan header's wattage limit of 8.88W?

No, what you are basically missing, and I am trying - at this point desperately - to try telling you is that if you connect a (say) 24 V device (or a 36 V or a 48 V or a 5 V or *whatever* voltage) to a 12 V outlet, the max voltage present at the outlet will remain 12 V, it is what "comes out" of the outlet and not the specs of the device attached to it.

The specific device (fan) can run continuously at 12.8 V but it is designed to be powered at 12V (i.e. it has a target of being operated at 12 V though it can accept as low as 6V and as much as 12.8V).

Power absorption is another matter, if you attach a device rated for a higher power absorption (but within the right Voltage specs) to a power outlet, the device will attempt to get more power (up to it's own specifications).

As a matter of fact when you connect a load to a voltage output, the voltage level might drop a little, but NEVER increase, if your motherboard ouputs 12V (as a matter of fact, if you had a mutimeter, you would measure on it - as said - most probably 12.2 or 12.3 V with no load connected to it and exactly 12 V or more likely 11.9 V with a "heavy" load connected) you will NEVER be able to get 12.8V from it.

Examples (simplified, and in order to let you understand) in case of BOTH an unprotected/unlimited power supply and of an unprotected/unlimited device:

Power supply specs:

12V 1A hence 12W

1. If you attach to it a device rated 6V 1A (6W) continuous, the device will burn in no time (because the voltage operating range of the device is greatly exceeded) .
2. If you attach to it a device rated 12V 1A (12W) continuous, both the device and power supply will work for years without issues (this device may well have peaks or "MAX" of up to 40% more than standard absorption - or even higher "transient" current spikes without any consequences to the device or to the power supply)
3. If you attach to it a device rated 6V 2A (12W) continuous the power supply OR the device will burn in no time.(because the voltage operating range of the device is greatly exceeded OR the current capabilities of the power supply are greatly exceeded)
4. If you attach to it a device rated 24V 1A (24W) continuous the power supply is very likely to burn (because the device will attempt to draw more current to compensate for the lower voltage)

http://en.wikipedia.org/wiki/Ohm's_law

that is the same, written differently, that gives you V x A = W (when talking of DC, NOT AC)

http://www.csgnetwork.com/ohmslaw2.html

the MAX current that device will draw is 0.70A at 12V, if you supply it with a higher voltage, let's say 12.8V it will draw LESS current, i.e.

12 x 0.70 = 12.8 x X -> X=~0.66 A

If you attach to an outlet (BTW surely protected from overcurrents) rated for 12 V 0.74A that particular fan, it will run normally at 12V (and NOT at any higher voltage) absorbing normally 0.51A with the possibility of peaks up to 0.70A.

The outlet can provide UP TO 0.74A at 12V (8.88W), the device will nornally use 0.51A at 12V (6.12W) with peaks up to 0.70A at 12V (8.40W).

You are well within the specs.

jaclaz

Thank you for confirming the fan is OK for my system. I needed to be sure to avoid damage. Just one last thing, are all motherboard fan headers protected from overcurrent? Also, if you store a fan for years and then decide to use it someday, would the oil on the bearings be dried up and the fan useless, or would the fan work like the day you bought it because the fan and the oil were never worked?

Edited by vipejc
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Thank you for confirming the fan is OK for my system. I needed to be sure to avoid damage. Just one last thing, are all motherboard fan headers protected from overcurrent? Also, if you store a fan for years and then decide to use it someday, would the oil on the bearings be dried up and the fan useless, or would the fan work like the day you bought it because the fan and the oil were never worked?

We are getting at every post nearer to :

http://www.imdb.com/title/tt0074860/quotes?qt=qt0247572

What one normally do would be:

1. connect the fan to a 12V DC power source (directly coming from the PSU
2. observe if it starts spinning
3. if NO goto 10
4. if Yes goto 5
5. let the motor warm a little, let's say by having it spin 15 minutes
6. connect it through a multimeter to the same power source
7. measure the amount of current it absorbs at start and when fully spinning
8. if current is within specs, goto END and mount it to the case
9. if current is above specs goto 10
10. remove (carefully) the label of the fan
11. remove the little retaining washer underneath
12. disassemble the fan from the motor
13. clean whatever residual of oil/grease is there
14. spray the bearing with some WD40 or similar
15. apply a tiny quantity of Superlube grease or similar
16. re-assemble the fan
17. goto 1

jaclaz

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I would insert between 1 and 2:

1a. Take a safe distance.

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