PC fan connectors

cookie_365 · 28-05-2005, 11:09

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?

Ta!

Graham M · 28-05-2005, 11:20

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.

cookie_365 · 28-05-2005, 11:25

Thanks Zeph !

Have a greenie on me

Matth · 29-05-2005, 16:00

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.

jonifen · 29-05-2005, 16:03

Quote:

Originally Posted by Matth

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

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?

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

29-05-2005, 16:11

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

cookie_365 · 29-05-2005, 17:28

Quote:

Originally Posted by Matth

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.

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.

Graham M · 29-05-2005, 22:29

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.

AndrewJ · 29-05-2005, 22:55

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.

Jonboy · 29-05-2005, 23:22

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

cookie_365 · 30-05-2005, 09:58

Quote:

Originally Posted by Jonboy

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

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

30-05-2005, 11:37

Quote:

Originally Posted by cookie_365

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

Surely the fact you want one is reason enough

bdav · 30-05-2005, 11:42

Quote:

Originally Posted by Jonboy

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

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.

zoombini · 30-05-2005, 13:21

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.

Graham M · 30-05-2005, 19:41

echo