My bios fan controller utility (Asus FanXpert) won't spin them down any lower than ~950 rpm.
According to FanXpert this is 20% of full speed (even though Scythe rates them at 200-1300rpm).

My sys and cpu temps are at ~24 degrees. Under sustained heavy load I can get the CPU up to 40 degrees.
Seems to be plenty of room to slow the fans down. I would like to try running them as low as 600rpm or lower.

I tried my best to make it happen with SpeedFan, to no avail.

Is a fan controller the only other option?


Fans: Scythe SY1225SL12LM-P 120mm

Thanks!

Same fan here running at around 400 rpm with higher sys and cpu temps than you. What are you BIOS settings? Do you have a choice of pre-set profiles in the BIOS and if so is Silent set as the default?

I'd love to get my fans going that slowly/quietly!

My bios fan control is set to "silent" (other options include "standard", "turbo", etc.)

Asus FanXpert also allows for user-defined profiles, but the fan speed value can't be set any lower than 20%, and unfortunately FanXpert considers 20% to be ~950rpm. Bummer.

Is there some sort of inline adaptor (like Noctua's ULNA) than could slow these fans down? Would something like that even work?

Noctua NA-RC6...

It is somewhat "strange" such a fan does not lowers its speed under ~950rpm :/

I would try uninstalling Fan Xpert and see what results you get with just the BIOS.

It is probably some form on interaction between the Asus BIOS settings and Fan Xpert. Certainly at 20% PWM duty cycle this particular fan should be running at considerably less than 950 rpm.

I'll try uninstalling FanXpert, but as far as I can tell it's really just a GUI pasted onto the bios controls, so prob. will be no change.

I'm sure the fan itself is fine. I suspect the Asus bios fan control just isn't set up for heavy tweaking.

Too bad, I bet I could spin these fans down to barely audible and still have a nice cool machine.

It doesn't look like the Noctua NA-RC6 can be purchased separately -- only avail. as part of a fan package. Can't find it as a separate item on the Noctua site, newegg, etc.

I would have gladly bought the Noctua NF-F12, which includes the NA-RC6 low-noise adaptor, if I had known I'd run into this issue. In my crazy effort to get the ultimate quiet PC, I put the 2 scythes in to replace a pair of perfectly good 3-speed/molex Antec fans. Sure hope I don't have to buy *another* pair of fans.

There must be an easy way to get these scythes down to ~400rpm.

Ok here is the trick, and this is totally up to you.

There have been reports that Gene Z (mine), into which some users could lower the rpm others couldnt pass the restrictions of the mobo (i think its 60% of case fans), but there were a lot of versions of FanXpert, some had success with older versions, so my recommendation is to test different versions and see if one allows you to do what you want, remember also to check bios updates.

Btw i own one of the Slipstreams PWM but never tested on my Asus Gene Z, but on my intel mobo it can be drop down to 250rpm.

The PWM fan of my previous Scythe Mugen 2 (the same model as yours I believe) could also be dialed down to 300 rpm with FanXpert. This was with mainboard ASUS M4aTD-m EVO/USB3.

Perhaps you could contact ASUS or uninstall/install FanXpert, or download another version of ASUS FanXpert?

Thanks for all the suggestions!

I tried two versions of FanXpert (as it comes bundled into the Asus "AI Suite"). Versions 1.05.22 and 1.05.33

Tried disabling fan controls in the bios and setting them only in FanXpert
Tried setting fan controls only in the bios and uninstalling FanXpert
Tried in XP and Win7 (I have a dual boot system)

No luck.

FanXpert is definitely controlling the fans. It will spin them faster/slower, but ONLY between ~950-1300rpm.

Bummer!

I have a few days left in the store warrantee on the Scythes. I could take them back and get Noctua fans instead. Are they the next best thing?

Apparently some of the Asus fan headers only use voltage, not PWM to control fans. That explains why FanXpert has been controlling one of my 3-pin fans.
Maybe this explains the issue I'm having, because I am using PWM fans. Might be exchanging the Scythes for some Noctua's

Here's what a Asus forum moderator said, albeit in ref. to a different mobo than mine...

"these fan headers... Apparently, they are set up to use DC control on a PWM fan. That is why there is a +5v pin. Normally, a PWM fan header supplys 12vdc all the time... and the pulse frequency controls the speed of the fan.

These headers have both a 12vdc and a 5vdc pin which allows the system to vary the voltage to the fan header... which is not possible with a standard PWM header.

The result is that a PWM fan can be controlled through Voltage variation on this sort of header... So whether you connect a 4wire PWM fan or a 3wire DC fan, the FanXpert and Q-Fan features can control the fan speed through voltage variation just like any other Asus board with just 3pin chassis fan headers. "


http://vip.asus.com/forum/view.aspx?board_id=1&model=P7P55D-E&id=20100819133349937&page=1&SLanguage=en-us

To summarize...

Current Asus boards come with a rats nest of mixed fan headers.
The CPU fan headers are always PWM (so I'm totally SNAFU'd with my new Noctua NH-D14 -- its fans are DC)
The chassis fan headers are always DC controlled

Only 3 of the 5-6 headers on the board are supported by FanXpert.

E.g. On the P5Q Pro Turbo FanXpert supports one CPU header (PWM) and two chassis headers (DC)
E.g. On the P8Z68-V-Pro Gen3, FanXpert supports two CPU headers (PWM) and one chassis header (DC)

On the P8Z68-V-Pro Gen3 board, one of the DC chassis headers has 4 pins (Ground, Fan Power, Fan In, +5v), even though it's not PWM. Confused yet?

I figured all this out because I own both boards and I'm trying to slow the darn fans down.

When it comes to fan control, I'd say the Asus mobos are 2nd class.

I have Sycthe PWM fans on a P8P67-pro and I can confirm that the can go well below 950 RPM, but ONLY if connected to the CPU header. The other headers are voltage controlled as you found out, even if they are 4 pin.

At least according to the manuals, all the new Z77 based ASUS boards have true PWM control for all 4 pin headers.

In my opinion Asus boards are perfectly OK (as are virtually any other make of motherboard) if you are using PWM control for 4 pin PWM CPU fans and 3 pin fans are run from chassis fan headers. In this scenario, if you need to run PWM chassis fans the best solution is a splitter cable such as the AK-CB002. So you could chain a PWM CPU fan with a PWM exhaust fan for example.

Running your Noctua NH-D14 with its 3 pin fans and using Scythe PWM fans as chassis fans is obviously the reverse of what the motherboard manufacturer expects. To me the simple solution is to use the Scythe PWM fans on the Noctua. This would require a simple PWM Y splitter cable. It would give you excellent control over the CPU fans using either the BIOS controls and/or Fan Xpert. I would redeploy the Noctua fans as chassis fans run from the 3 pin fan headers. From what the SPCR review found http://www.silentpcreview.com/article1020-page7.html the NH-D14 will work perfectly OK with Scythe PWM fans.

thanks for the excellent suggestions. I'll be putting PWM splitters in every PWM-configured header on my boards. I'm even thinking of splitting one side of a split line for a total of 3 PWM fans (is that a bad idea?)

From what I've read, many mobo's allow fan headers to be switched between PWM or DC control, in the bios or with jumpers (unlike Asus' fixed configurations). Seems Asus is also unaware of the new generation of high efficiency, low rpm fans. If any fans on an Asus board are set to run below 600rpm, the bios boot will hang with a "Fan Error!".
Someone figured out a workaround for this, but it only works on newer boards (see post # 9)...

http://vip.asus.com/forum/view.aspx?board_id=1&model=P7P55D+EVO&id=20100828043029646&page=1&SLanguage=en-us

Give speedfan another go. Configure --> advanced tab and select your i/o chip. Look for any "PWM" related settings and change to manual mode, ticking "remember it". It must work.

If Q-Fan is enabled in the BIOS it will also activate the CPU Fan Speed Low Limit. By default this is set to 600 rpm. The alternatives for this setting may vary depending on the motherboard concerned, but there should be an 'Ignore' option. With PWM fans I normally just set this to 'Ignore'. As you might expect, there is also a Chassis Fan Speed Low Limit and again it is set to 600 rpm by default. As with the CPU fan there will be an 'Ignore' option for this setting.

thanks again all for the suggestions.

Does anyone have an opinion on splitting a PWM fan header twice? One Y-cable into the header, then another Y-cable into one end of the first Y-cable. Safe to do something like this?

Find out what the max amperage that the fan header can supply. It's usually 1 or 2 amps. Then add up the amp ratings on all your fans and make sure you don't go over.

I've got three fans (two on the heatsink in push-pull and rear exhaust) on the CPU header with splitters and it works fine.

I also have seen a 1 to 4 PWM splitter cable that got power from a molex and only used the fan header for the PWM control signal. Haven't seen it available for a while though.

Only once i've seen in a mobo manual the max amperage for a fan header. To be on the safe side, try not to go over ~1A.

I've got 4 d12sl Yate loons in a chain, on the same header and had no issue. They are rated 0.3A and stay 95% of the time at 500RPM and go at 800 when needed.

Provide a picture like the one posted by me earlier and maybe we can make speedfan work. It's the "must have" tool for silencers.

I would recommend to get Akasa SMART PWM Fan Cable Adapter AK-CBFA03-45, its safe to use up to 5 fan with it, as it only uses the PWM signal from the mobo, but supplies the power via the PSU 4pin molex. Im using one my HTPCMI build (check sig), no issues at all.