PC fan connectors
 

You know those 3 prong fan connectors you get on most motherboards these days?

Are there any advantages/disadvantages to using them as opposed to ordinary power connectors coming out of the power supply?

I've just replaced my old system fan; the old one connected to the power supply, but the new one had a 3 prong connector so I used that. It seems to be working fine; the only thing is, the connector labelled 'system fan' on the mobo was inaccessible so I connected to the one marked 'chipset fan'. Will that make a difference? :confused:

Ta!

Re: PC fan connectors
 

The only thing special about the 3 pin fan headers on the motherbaord is, not only do they supply the fan with power but they also send the speed of the fan's rotation back to the motherboard. Certain motherboards will power down the system if the CPU fan stops for instance and you can use monitoring tools in Windows and the BIOS to see how fast the fans are spinning, some motherboards will even control the fan speeds automatically to keep your PC cool but, when possible (IE low CPU usage, etc.) quiet.

Re: PC fan connectors
 

Thanks Zeph !

Have a greenie on me :)

Re: PC fan connectors
 

No chipset fan? - I'd expect that to be used already?

My old system had.. CPU Fan, Power Fan, System fan - some PSU's have a "RPM indicating" connection that plugs into a fan connector, so the PSU fan speed can be monitored. I used them for a front and rear fan set

One important point to note is that you cannot use the 3 pin power for "extreme" fans such as high CFM/noise Delta's.

Re: PC fan connectors
 

Is that because the system could not report such a high RPM for the fan? Or is it because they're that damn loud you'd hear it not working before the PC reported it? :D

But I didnt know that... have a greenie.

Re: PC fan connectors
 

I dunno about mentioned fans,but the high speed controlable fans ive used have come with a molex connector for power and a 3 pin plug with just one connection for motherboard monitoring of speed and temp.If the cpu fan does not have this then the pc will not boot as motherboard will think fan has failed

Re: PC fan connectors
 

Thanks Matth- nothing previously in 'chipset' fan; there's also a CPU fan (which I'm relieved to report is occupied already!) and the graphics card has it's own fan.

Plus there's the fan in the power supply.

All seems to be running OK with the chipset fan connection.

Re: PC fan connectors
 

The chipset on my motherboard has no fan, and quite a small heatsink, it depends on the model really. Sometimes there is just no need for one.

Re: PC fan connectors
 

My Micro ATX Asus Pci-E mobo has a tiny one on its Nforce4 chipset, and a intake on the side of the tower, a case fan, and a huge CPU fan and heatsink.

Re: PC fan connectors
 

the only fans i would run off the motherboard is the cpu fan, i would run all other fans off the psu the way motherboards are made nower days i would not trust the tracks on the motherboard to cope with the power that some of these fans use they are wafer thin now, and you could end up with a burnt out track on the board within a few months down the line not easy to fix, as long as you have a good 400w psu run yer fans from that

Re: PC fan connectors
 

Thanks Jonboy - next time I've got the PC open I'll look at the options again. :)

Though if it does fail while connected to the mobo at least I'll have an excuse to buy myself a new PC ;)

Re: PC fan connectors
 

Surely the fact you want one is reason enough :LOL:

Re: PC fan connectors
 

THe difference between running a fan off the MoBo and the PSU makes no difference to the power consumption - it all comes from the PSU anyway.

Re: PC fan connectors
 

The third connection (usually middle pin) as well as sending back the speed, can also be used to control the speed of the fan.

Because of the monitoring functions on mobo's these days it is much better to use these connectors (Molex KK range) instead of the std PSU ones.

Re: PC fan connectors
 

echo :)

Re: PC fan connectors
 

i am not saying it makes a power difference,
what i am saying is the tracks on the motherboard can cope with the odd cpu fan and smaller system/north/southbridge fans but i would not trust running the larger fans used for case cooling due to the thin tracks now used on the newer motherboards i would rather hook them up to the molex from the psu.
people dont realise electric current moves and any movement causes friction and friction causes heat why take the risk of burning a track out if you dont have to .

Re: PC fan connectors
 

And are you aware exactly how much current that those tracks can carry?
A 0.01" track (0.25mm) can carry 700ma without drawing a sweat, so even the thinner 0.005" ones (if they go down to that) can carry enough to cope with a case fan that takes only a few hundred milliamps & any going to a fan supply socket is going to be thicker than the thin signal ones. :D

Re: PC fan connectors
 

The main reason they are not recommended for beasts like the 80mm 80CFM Delta
http://www.sidewindercomputers.com/del80ffb08123.html
is that the beast draws 0.9A instaed of the usual 0.2A or thereabouts for more normal fans.

While a copper track would need to be very thin to burn out at that level, the motherboard fan power may also be fed through a PWM switching control, on those boards that bother to implement it - users of Almico Speedfan http://www.almico.com/speedfan.php will find that while many chipsets support PWM speed control, many motherboard makers don't add the components to do the switching.