Power all fans from MB headers or use PSU?

Lou_H · Post by **Lou_H** » Sat Jan 12, 2008 10:42 am

My new Gigabyte GA-P35-DS4 MB has five fan headers.
If I use the MB fan headers I can use the small fan cables, plugs and less adaptors,
but I have all 120mm fans and I am worried that they might be too much load on the MB. I canâ€™t find any info about maximum watts for these MB's fan headers.
Right now I have:
Two Sythe S-Flex SFFF21E 1200 rpm 120mm fans at 1000rpm with Zalman Fanmates and
One SFF21D 800rpm fan at full 12V.
I might add another 100mm fan after more temp testing.

Would it be hard on the MB circuits to run these fans?
Should I run the fans off the PSU or is OK to use the motherboard headers?

quadraphonic · Post by **quadraphonic** » Sun Jan 13, 2008 9:15 am

First I guess I'd ask why you feel you need so many fans. I have a P35-DS3P and have three fans running off the mobo, 2 120mm (1 S-Flex D, 1 S-Flex E), and a 92 mm (Nexus Real Silent). They are sufficient for cooling and my S-Flex E, and Nexus seldom run at full speed.

Power-wise, I can't say I've run into any problems yet. I'm running a Corsair HX520 for a PSU.

Lou_H · Post by **Lou_H** » Sun Jan 13, 2008 12:10 pm

I donâ€™t plan on using all the fan headers. I have it running OK right now with three fans. One exhaust for the case, one for CPU and one for the VGA card. I have modified several older PC's to be quiet, but have not put together a new PC in about four years. The last PC I put together had known issues with capacitors going bad, and most cases used smaller fans, so I was always worried about using the fan headers for big 120mm fans. The current MB's seem to have very large NB and SB heat sinks and more power in connecters, so maybe they are made to handle the larger 120mm fans.
Also my last video card had a known problem with the voltage regulator overheating because there was no cooling to it. So I thought that because I am using a Thermalright Ultra 120-E CPU cooler that does not blow air down on the MB, I have no Northbridge cooler, and that maybe a 120mm fan would heat parts of the MB that are not getting cooled by direct air flow, then I might by stressing parts on the MB.

I thought that maybe I should use a Sythe 100mm fan to blow air across the MB to help cool it, but then thatâ€™s another fan connected to the headers.
So if most users are using large 120mm fans with the MB headers and no problems with the MB passively cooled then I should be OK.

quadraphonic · Post by **quadraphonic** » Sun Jan 13, 2008 1:10 pm

I think you should be ok. My fans are running in an Antec Solo (1 HD, 1 CPU, 1 exhaust). Of course there are also the PSU and GPU fans. At any rate, the mobo's temps have been fine, everything runs well and power just hasn't been an issue (that's using three of the four fan headers).

Conroy · Post by **Conroy** » Sun Jan 13, 2008 2:29 pm

quadraphonic wrote:First I guess I'd ask why you feel you need so many fans. I have a P35-DS3P and have three fans running off the mobo, 2 120mm (1 S-Flex D, 1 S-Flex E), and a 92 mm (Nexus Real Silent). They are sufficient for cooling and my S-Flex E, and Nexus seldom run at full speed.

I'm sorry to borrow this thread, but I have a question for quadraphonic.
I understood that the P35-ds3p only had one controllable fan header, and it was the 4-pin pwm kind, so I've been wondering how to control my s-flexes and nexus. It sounds like your motherboard is controlling yours?

Scoop · Post by **Scoop** » Sun Jan 13, 2008 2:35 pm

Why would they put five fan headers on the board if it couldn't handle them?

quadraphonic · Post by **quadraphonic** » Sun Jan 13, 2008 3:00 pm

Conroy wrote:
quadraphonic wrote:First I guess I'd ask why you feel you need so many fans. I have a P35-DS3P and have three fans running off the mobo, 2 120mm (1 S-Flex D, 1 S-Flex E), and a 92 mm (Nexus Real Silent). They are sufficient for cooling and my S-Flex E, and Nexus seldom run at full speed.
I'm sorry to borrow this thread, but I have a question for quadraphonic.
I understood that the P35-ds3p only had one controllable fan header, and it was the 4-pin pwm kind, so I've been wondering how to control my s-flexes and nexus. It sounds like your motherboard is controlling yours?

There should be 2 PWM adjustable headers, CPU FAN and SYS FAN 2 (in which I have my CPU fan and HD fans plugged in respectively. In the BIOS, I have Smart Fan Control Method and Mode set to auto. This generally keeps both of those fans running at 50-60% rpm. For exhaust, my S-Flex D is plugged into SYS FAN 1 and runs at 100%. Aside, from undervolting / fan controllers, I don't believe there are any other ways to modulate speed from either SYS FAN 1 or PWR FAN as they are 3 pin headers, missing the fan control lead.

For those two 4 pin headers you can set up Speedfan to manage rpms.