Replaced PSU, now case fan runs 100% - could I use a 4-pin to 3-pin adapter?

[infinitesymphony]

A fan-related question...

The stock 380-watt Antec power supply in my parents' Antec Sonata case died, so I replaced it with a Corsair CMPSU-400CX. It works well, but the rear case fan is now spinning at 100% and cannot be controlled with applications like SpeedFan.

The Antec PSU had a 3-pin, two-wire cable that connected to the PWR_FAN header on the motherboard; this new power supply does not have any 3-pin connectors. I'm assuming the old PSU was communicating the case fan speed to the motherboard. If I use a 4-pin to 3-pin adapter to connect the case fan directly to the PWR_FAN header on the motherboard, will that give me the same amount of control as before?

An example of a 4-pin to 3-pin adapter (4-pin side on the right)

My case has turned from near-silence into a white noise machine. Any help would be appreciated.

 

[Quiksilver]

Yes.

Edit:

Wait, I misread your question.
The old 2pin connector from your old PSU was for the power supply fan. It had nothing to do with any case fans. The new PSU doesn't have one because it's thermally controlled inside the PSU; so it wasn't needed.

So the question would be is the problematic case fan being powered with a 4 pin molex which would cause it tor un 100% all the time or Is the fan using a 3 pin molex which has the RPM sensor and can speed up/ slow down accordingly.

 

[infinitesymphony]

The fan itself (a stock Antec) has two 4-pin Molex connectors on the same run, one male, one female. It was plugged into a 4-pin Molex on the old PSU as well.

 

[rarebear]

My new Rosewill PSU has a switch in back for LAH

Low Auto and High

I would think yours would have something as mine is pretty low end unit..

 

[infinitesymphony]

The PSU fan isn't the issue, it's the rear exhaust case fan making all the noise. As far as I can tell, it was plugged in the same way on the old PSU, but before, it was software-controllable and running at lower RPM.

 

[Zepper]

The two wire connector from the PSU was the speed sensor from the PSU fan, so you could know if the fan died if you wanted to (as rarely does a PSU fan obtain power anywhere but internally to the PSU and the thermal control is in the PSU as well. If there was a special Molex connector for the case fan on your old PSU, then the case fan was also controlled by the thermal control in the PSU (that's stupid IMO). If you want to control your case fan with the new PSU, your fan connector on the mobo will have to be capable of it itself or you'll need a separate fan controller or you can get a thermally controlled fan (has its own NTC thermistor). I like to control them myself, so I use a separate controller.

Very few mobos I know of have a "PWR_Fan" connector on them... They have a CPU FAN and one or two AUX or Case fan headers which are generally uncontrolled.

.bh.

 

[infinitesymphony]

Ah, here's why:

"Another great feature this PSU has is two (2) included connections specifically for the case fans (2 x 120mm) labeled 'Fan Only.' Using these connections instead of the other, normal, molex connections, will cause your case fans speed to be dependent on the case temperature, slowing down and lowering the fan noise when only a little airflow is needed. This is because the PSU uses 'Antec Low Noise Technology' circuitry."

So it was something uncommon to most power supplies. What's the cheapest option now? Two Zalman Fan Mate 2s?

Edit: I see that the Fan Mate 2 is for 3-pin fans. Ugh... I didn't anticipate having to replace two 120mm fans just to keep the noise down. I'll probably end up paying more for the fan equipment than I paid for the new PSU.

 

[infinitesymphony]

What would you guys do in my situation? I need to control two fans that have 4-pin power connectors.

1. 4-pin to 3-pin adapters + a fan controller / fan controllers?
2. two new fans with selectable speed (ex. Antec TriCool)?
3. two new fans with built-in thermistors (ex. Antec SmartCool)?

If you'd choose one of the latter two, what makes/models would you recommend. I appreciate your advice--if you're in this forum, cooling must be your forté.

 

[Zepper]

A Sunbeam Rheobus doesn't cost much more than two Zalman FM2s (at places like http://www.Jab-tech.com et al.) and can handle up to 4 (or more if you double up the fans on each connector - yes, 3-pin power Ys are available.) fans. If you get a Rheobus, you'll also likely need some fan extensions as the Rheo. doesn't come equipped with them. OTOH your molex to 3-pin adapter may suffice as the extension as well.

.bh.