Using Nexus Fan to cool Scythe Ninja..hook up power to Mobo?

theoryzero · Post by **theoryzero** » Wed Jul 19, 2006 9:58 pm

Ok, the motherboard I'm planning to get for my new system (Asus P5W DH) has a 4-pin CPU fan power plug on the board. I was planning to get a Scythe Ninja and use a Nexus fan to cool it. I know the Nexus has the standard small 3-pin plug and 4-pin molex plug on it. Can I just connect the 3-pin plug to the 4-pin jack as long as I don't use the PWM pin?

Also, I got a bunch of NMT-3s because Silicon Acoustics is going out of business. Has any tried to incorporate one of these to control the CPU fan output?

Thanks,
TZ

gb115b · Post by **gb115b** » Thu Jul 20, 2006 5:21 am

thats a PWM fan connector....not sure how you convert them, but am interested in getting this MB too to would be good to know...

cmthomson · Post by **cmthomson** » Fri Jul 21, 2006 7:15 am

Yes, just plug the 3-pin connector into the 4-pin CPU fan plug. It will run at 12V unless you've enabled voltage-based fan control on the motherboard (Q-Fan mode DC). You can probably used SpeedFan to control this.

I use NMT-3's on two of my Nexus fans: the top case fan and the power supply/hard disk fan (I have a P180).

You could use an NMT-3 on a CPU fan, but it probably wouldn't work too well as a speed controller since if you put it on the cool air side it would probably always run at 5V, and if you put it on the warm air side it would probably always run at 12V.

That said, if they're just lying around, an NMT-3 is a really easy way to undervolt a fan to 5V if the ambient temperature is below 28*C. It has the advantage over a resistor of starting the fan at 12V, then slowing it down after a few seconds. This is good because many Nexus fans need about 6V at startup.

Tzupy · Post by **Tzupy** » Fri Jul 21, 2006 8:26 am

Are you sure it's 100% safe to do that?
I hope you are right, since I have bought Nexus fans and all new mobos have now PWM fan headers.
It would be great to use BIOS based fan control on the new mobos, I was planning to use my old fan controller.

theoryzero · Post by **theoryzero** » Fri Jul 21, 2006 10:35 am

cmthomson:

Yes, I was planning to use the NMT-3 on the CPU fan and expect it to just use the ambient temp. I figured it would keep the speed low and I don't have to go find one of those Zalman 7v resistor cables. I now have 5 of them from the sale, so I do have some just laying around.

When using the NMT-3 with a Nexus fan, it seems like there are lots of extra cable. I'd like to re-wire it without the 4-pin Molex connections. Is there a tutorial on how to do this? Not sure if I need a special tool to wire the 3-pin connection or not.

theoryzero · Post by **theoryzero** » Fri Jul 21, 2006 11:21 am

Nevermind, found the answer to my question about removing the 4-pin molex stuff.

cmthomson · Post by **cmthomson** » Fri Jul 21, 2006 3:07 pm

Tzupy wrote:Are you sure it's 100% safe to do that?
I hope you are right, since I have bought Nexus fans and all new mobos have now PWM fan headers.
It would be great to use BIOS based fan control on the new mobos, I was planning to use my old fan controller.

New high-end motherboards (including the P5W DH Deluxe quoted above) support both PWM on the fourth pin of the CPU fan connector, as well as DC voltage control on the second pin, or neither (12V only) as BIOS options. The GA-965P-DQ6 also has this.

An older motherboard (such as a P5LD2) has only PWM or 12V, no DC control. If you plug a 3-pin connector into the 4-pin header on one of these, the fan will always be 12V. Note this is perfectly safe: the header is keyed so you can't plug in to the wrong pins.

cmthomson · Post by **cmthomson** » Fri Jul 21, 2006 3:12 pm

theoryzero wrote:cmthomson:

Yes, I was planning to use the NMT-3 on the CPU fan and expect it to just use the ambient temp. I figured it would keep the speed low and I don't have to go find one of those Zalman 7v resistor cables. I now have 5 of them from the sale, so I do have some just laying around.

When using the NMT-3 with a Nexus fan, it seems like there are lots of extra cable. I'd like to re-wire it without the 4-pin Molex connections. Is there a tutorial on how to do this? Not sure if I need a special tool to wire the 3-pin connection or not.

Well by all means give that a try. Put the NMT-3 on the fresh air side of the fan. But you should also consider configuring your BIOS to DC fan control and either using the built-in control software or SpeedFan.

As for tools, cutter/stripper and needle-nose pliers are all that are needed for assembly (and the plug casing and inserts of course). To disassemble, you also need a jeweler's screwdriver.