OK to run 120mm fans from MB headers?

[NTB]

about to build a new C2D system using a Thermalright ultra-120 extreme w/an S-Flex 120mm fan. Normally I'd run a fan this size straight from the PSU, but I'd like to be able to monitor the fan speed for this particular one. So, should I run it from the MB header or not?

Nathan

 

[lenjack]

your mobo manual will tell you how many watts or amps the connectors can handle safely, and the fan hub will have the same info on it. If the fan uses less power than the mobo limit, it's a go.

 

[NTB]

Originally posted by: lenjack
your mobo manual will tell you how many watts or amps the connectors can handle safely, and the fan hub will have the same info on it. If the fan uses less power than the mobo limit, it's a go.

In that case, using the fan headers shouldn't be a problem. From the Asus P5B manual:

The fan connectors support cooling fans of 350mA ~ 2000mA (24W max), or a total of 1A ~ 7A (84W max) at +12v

The 120mm fan I have is a Scythe S-Flex 1600RPM model:

12V/0.20A = 2.4W

Nathan

 

[Billb2]

4.8 on startup probably.

 

[VERTIGGO]

Sounds like you're trying to scare him! I've been running about 4 fans off the mobo power for several years. One is a Panaflo 225CFM and several are LED 115CFM fans. np

 

[hardbench]

Should be fine, but it is always preferred to run fans straight off of the powere supply connectors for a variety of reasons, especially when overclocking.

 

[imported_Willie]

Never had a problem with running typical 120mm fans off the headers, LED or otherwise, overclocking or otherwise.

I say typical because there are the oddball 120 x 38mm fans that are huge current draws, but the S-Flex certainly isn't one of them. You could fill all your headers with them and face no problem at all.

 

[imported_Willie]

Originally posted by: Billb2
4.8 on startup probably.

Probably wrong. Startup voltage on the S-Flex "E" is 4.8V, or less than 1W, and the S-Flex "F" has a startup voltage of 4.0V, or again less than 1W. The S-Flex "D" has a higher startup voltage of 8.9V, or 1.78W.

Figures courtesy of Silent PC Review testing of the three S-Flex fans....first 120mm fan roundup.

So, they nowhere approach doubling their normal +12V running wattage; their startup voltage/wattage is MUCH less.

Rather poor try at guessing and trying to spread some fear into the guy!