Gigabyte 4-pin sys fan, 5V vs. 12V?

ptr727 · Post by **ptr727** » Mon Aug 18, 2008 8:20 am

Hi, I am considering gettng a Gigabyte EP45-DS3R motherboard.

The manual indicates that the system fan control header is a 4-pin, with 5V power.

See page 24, SYS_FAN2:
Pin-1 = Ground,
Pin-2 = Speed Control,
Pin-3 = Sense,
Pin-4 = +5V,

As far as I know the 4-pin PWM fans are 12V and not 5V, and is this the correct pin laynout for these fans?

I compared this against the GA-X48-DQ6 manual, and it is exactly the same.

Is this maybe a typo in the manuals, or do I need to look for different fans?

Regards
P.

nomoon · Post by **nomoon** » Mon Aug 18, 2008 11:49 am

I have this board and it appears to be +5 volts. A 3-wire fan runs slowly when connected to this header. However, when I connected a Fanmate2 to this header, it didn't seem to have much of an effect on fan speed. I'm not sure what to make of that. I haven't yet connected a 4-wire pwn fan to this header.

I contacted Gigabyte about why the manual's chart indicates that pins 2 and 4 are reversed from the CPU pin out. Their response was that there is a typo in the manual.

FYI: Here is my email to Gigabyte followed by their response:

1. Is it possible to control the fan speeds for fans connected to headers other than CPU_FAN? What about SYS_FAN1, SYS_FAN2, and PWR_FAN?

2. Is it possible to change the setting in BIOS from "PWM controlled" to "Voltage controlled" on this motherboard? I understand that it was possible on previous Gigabyte motherboards.

Page 37 of the manual states that advanced options in the BIOS can be accessed by pressing +. Does this feature work in the F7 BIOS for this board? It doesnâ€™t seem to be working for me when I press it at the Main Menu or at the PC Health Status menu.

Page 24 of the manual states that SYS_FAN2â€™s pins 2 and 4 are reversed from the normal pinout for a 4 pin PWM fan. Is this correct? What is the reason for this? On other fan headers, I can use a FanMate2 to reduce the fan speed, though it doesnâ€™t work on fans connected to this header. Does software control affect this header at all?

FYI: I can use a program called Speedfan to monitor all fan speeds and to control a 4-wire PWM fan connected to CPU_FAN. I have not been able to control any 3 wire fans connected to any of the other headers. I havenâ€™t been able to control a 3 wire non-PWM fan using Speedfan on SYS_FAN2. Iâ€™m wondering whether the PWM function would be controllable if I re-soldiered the wires to reverse pins 2 and 4 on SYS_FAN2.

Thank you for your help!

1)Only the 4 pin header on the board when connected an 4 pin fan can be controlled, which is automatic. You will not be able to manually control it

2) setting to auto will detect all the proper fan which you have connected

CTRL + F1, only for advanced setting for overclockers, no additional options will be included under pc health status
If the software is able to detect the fan you can monitor it, but will not be able to adjust any settings for it, SYS_FAN 2 is the same as the cpu
There is an typo on the user manual, the layout are the same as cpu fan header

nafets · Post by **nafets** » Mon Aug 18, 2008 2:08 pm

As was the case with my Gigabyte GA-P35-DS3L, and now my current Gigabyte GA-EP45-DS3L, the SYS_FAN2 header is gimped and only outputs 5V, which makes it fairly useless.

I have had the same experience as nomoon, regarding it's usage.

I only use the SYS_FAN2 header for RPM monitoring for one of my Scythe S-Flex fans, which I have running at 12V through the molex adapter, included with the fan.

Why they can't just have it output 12V like the other fan headers, I can't understand...

ptr727 · Post by **ptr727** » Mon Aug 18, 2008 2:23 pm

Thank you for the replies.

This is rather weird then

Are there any 5V PWM chassis fans out there?

nomoon · Post by **nomoon** » Mon Aug 18, 2008 4:58 pm

I have a KAMA PWN Fan that I'll try to stick on sometime soon. I seem to remember reading in the specs that the startup voltage is around 7 volts, so it may stall at 5 volts. There's one way to find out.

FYI: I've been able to run another KAMA PWN Fan on the CPU header at ~350 rpm.

Lawrence Lee · Post by **Lawrence Lee** » Mon Aug 18, 2008 5:56 pm

That's very weird... if the fan is going to receive 5V no matter what, why bother making it a 4-pin? I'd be interested to see what happens if you use a PWM fan.

ptr727 · Post by **ptr727** » Mon Aug 18, 2008 7:44 pm

I would also be very interested to know how typical, e.g. Nexus, PWM fans behave when connected to this port on Gigabyte boards.

nomoon · Post by **nomoon** » Mon Aug 18, 2008 8:08 pm

I just connected my KAMA PWM Fan to the strange +5V connector. I only spent a few minutes investigating, so I may have missed a few things, but here are the key findings:

The fan stalled when I first booted. I could start and stop it with my fingers.
This header is controllable with Speedfan when using a PWM fan.
It is not controllable when using a non-PWM fan.
I was able to get the KAMA PWM to unstall when using Speedfan. It appears that maybe the default voltage is +5 volts, but the voltage can be increased via software. I'm not an expert on PWM fans, so maybe something else is going on.

Note: The CPU header works as expected. It can be use to control PWM fans. I don't know whether it can control a non-PWM fan.

ptr727 · Post by **ptr727** » Wed Aug 20, 2008 3:06 pm

The plot thickens...

Gigabyte support replied this when I asked them what 5V PWM fan to use with the EP-45-DS3R:
"The fan header is actually 12v, there is an typo on the user manual.
Any standard system fan should not be an issue with the board"

nafets · Post by **nafets** » Wed Aug 20, 2008 4:30 pm

Sure SYS_FAN2 is functional with any 12V fan, PWM or not, but the header is only supplied with 5V.

More like a wording boo boo...

ptr727 · Post by **ptr727** » Wed Aug 20, 2008 5:56 pm

Is there a dedicated gigabyte motherboard forum, similar to the ASUS VIP owners forum?

nomoon · Post by **nomoon** » Wed Aug 20, 2008 8:12 pm

This appears to be a Gigabyte forum, though I don't know whether it is an official Gigabyte forum. http://forums.tweaktown.com/f69/

I don't think that their support people really know what's going on with the fan headers. I think that the only typo may be in the wiring.

The Sys fan header is definitely behaves differently from the CPU PWM header:

My GlobalWin non-PWM fan operates at about 700 RPM when connected to this header. It runs at about 1300 RPM when connected to the other non-PWM headers. It runs at about 1300 RPM when conncted to my old ASUS mother board with non-PWM 12 volt headers.

At power up, my KAMA PWM fan that is connected to the CPU header starts up immediately at runs at about 1200 RPM. When I connect a KAMA PWM fan to the SYS PWM header, it stalls. However, I can unstall it if I bump the power to 100% inside speedfan.

Maybe this header is stuck at +5 volts when a non-PWM fan is connected to it. I'm not exactly sure how PWM fans work. Is there a possibility that its pulsing +12 volts with an equivalent power of 5 volts of continuous voltage?

ptr727 · Post by **ptr727** » Thu Aug 21, 2008 6:02 pm

I replied to Gigabyte support with a link to this thread, asking them if they are sure about the 12V, this is what they wrote back:
"We have double checked, the 4 pin system fan 2 does uses 12v"

nwrigley · Post by **nwrigley** » Thu Aug 21, 2008 8:10 pm

I've found the exact same behavior with the Sys2 fan header on my GIGABYTE GA-P35-DS3R board. Haven't tried it with a PWM fan, but it definitely undervolts 3 different 3-pin fans. I can also get them up to normal speed using SpeedFan.

seemingly.random · Post by **seemingly.random** » Thu Aug 21, 2008 8:14 pm

I have the gigabyte 780g micro atx mb. It has a 4pin pwm sys fan connector and is temperature controlled by the bios. In a cool room, a nexus 120mm won't even start on a cold start. Though, after the pc is running a few minutes and warms up a bit, the fan will run after getting a manual kick start.

I ended up getting a scythe 120mm pwm fan - 1200rpm. In a cool room, it spins ~500rpm - warm room, ~750. I have this in the front of the case blowing over the disk drives, so in a cool room I don't hear it at all. I wish there were two sys fan connections on this mb like it's big brother...