Northbridge fan annoying. Can I slow it down with a resistor in series?

[Muse]

I just bought a new Gigabyte GA-K8N Pro mobo (it's new but came out around 2003-4, I believe), a socket 754 board, and I'll have it running an AMD Athlon Venice 2.2 GHz 3200+ CPU and 2 GB of PC3200 memory (when I get it, for now it's a couple of sticks of 512 MB PC2700).

Posting the mobo yesterday I discovered that the northbridge fan is fairly loud. One of my priorities is making the system very quiet (it's my regular PC but I use it for HTPC a lot, too), plus I like to contemplate and read at the computer, so I like it real quiet.

I found out fast that just putting a finger over the NB fan increases the noise from it, so I removed the little grate that covers it, decreasing the restriction. The mobo will be mounted vertically, so I don't see the need for that grate, which was easily removed.

My last mobo, which died a month ago, had an NVIDIA® nForce3 250 Chipset, but the northbridge, which accommodating a fan, was supplied with no fan. Thus, I could have put a fan on it, but clearly the manufacturer (i.e. MSI) thought it wasn't required.

My new mobo has the previous nForce chipset, NVIDIA® nForce3 150, and I'm thinking that although the supplied fan on the northbridge might be a good idea (or even necessary), I'm also thinking that I can probably get away with slowing it down by decreasing the voltage, by putting a resistor in one of the two leads that go to the NB fan power connection on the mobo. I have a couple of resistors I bought from a local indie electronics shop expressly in order to slow down 80mm case fans:

47 ohm, 5 watt
27 ohm, 5 watt

Can I use one of these, and if so, which would be better?

TIA

 

[EarthwormJim]

Whats the current on the fan?

 

[Jessica69]

What size fan is it? If it's a 40mm, I'd recommend a Mini-Kaze to replace it. I bought one last weekend at MicroCenter on a whim.....for SB cooling on my Maximus Formula mb. I've moved to watercooling my NB along with the cpu, and the SB heatsink is sitting there lonely. So bought a Mini-Kaze....but, naturally thought it'd be another mini-tornado in sound.

Couldn't have been more wrong. For its size, lot of air flow and can barely hear it even when I held it right next to my ear, running at full speed. On the motherboard, silent. Darned impressive fan, to say the least.

 

[Muse]

Originally posted by: EarthwormJim
Whats the current on the fan?

It says:

Everflow
DC Fan&DC Motor
MODEL: S124010DM
DC 12V 0.08AMP
MADE IN CHINA

 

[Muse]

Originally posted by: Jessica69
What size fan is it? If it's a 40mm, I'd recommend a Mini-Kaze to replace it. I bought one last weekend at MicroCenter on a whim.....for SB cooling on my Maximus Formula mb. I've moved to watercooling my NB along with the cpu, and the SB heatsink is sitting there lonely. So bought a Mini-Kaze....but, naturally thought it'd be another mini-tornado in sound.

Couldn't have been more wrong. For its size, lot of air flow and can barely hear it even when I held it right next to my ear, running at full speed. On the motherboard, silent. Darned impressive fan, to say the least.

It is 40mm

How much was the mini-kaze?

The thing is, the fan has no casing other than a top plate. This allows it to cozy down into the heatsink, which has a circular cutout for the fan. If I put another 40mm fan on there (and I have one, although it's not necessarily an extremely quiet one either), it's apt to have to sit on top of the heatsink. That would work, but it wouldn't have the proximity of the fan blades that this Everflow fan has by virtue of its geometry. I think that it would probably make sense to quiet the thing down by reducing the voltage with a resistor, assuming that this Everflow fan at 12v is overkill, which I'm guessing is the case.

What kind of problems would/could I have if the NB overheated?

 

[Muse]

What I finally did was to apply both resistors (27 watt and 47 watt) in series. I had my reservations about modifying the NB fan on my new mobo, figuring that would void any warranties I have with the seller and the manufacturer. Looking, I found a NB fan in my collection that fits nicely enough, and it has the profile necessary to cozy into the heatsink. It is rated at 0.06 amps, so I figured that it might be quieter. It was actually just about as loud as the stock 0.08 amp fan that was on there.

I measured the amps and found that instead of drawing 0.06 amp it was actually drawing 0.048. With both resistors on there it drops to 0.037 amp and is almost inaudible. I doubt I will have any problems due to decreased cooling of the NB.

 

[Jessica69]

The Mini-Kaze was like $4.99, if I remember correctly.

Here's a link to the fan, but at Performance PC's....so you can see which one I'm talking about.....it's $4.95 from them......

http://www.performance-pcs.com...=123&products_id=22537


What's interesting is that the fan is 20mm thick, so it looks thick as all heck. But I guess its thickness works, because it moves as much air as a 40mm Delta screamer I have that has rpm's around 5,000 or better, and moves just as much air and is utterly silent, as well.

 

[EarthwormJim]

Probably running at about 9v now with those two resistors. As long as it's performing well and is quiet, no reason to get the kaze imo.

 

[Muse]

Originally posted by: EarthwormJim
Probably running at about 9v now with those two resistors. As long as it's performing well and is quiet, no reason to get the kaze imo.

If it is really that thick the kaze wouldn't work for me anyway. The NB is right next to and partially underneath the AGP card, and there's precious little clearance. I guess that's why they have the fan sunk into the heatsink. I was just lucky I had a nice fan that fit in there. If I didn't I probably would have used the one they supplied. But this works really well, as long as it keeps working. It's Taiwanese made, and on the fan it says "Hypro Bearing," whatever that means.

 

[EarthwormJim]

Originally posted by: Muse

Originally posted by: EarthwormJim
Probably running at about 9v now with those two resistors. As long as it's performing well and is quiet, no reason to get the kaze imo.

If it is really that thick the kaze wouldn't work for me anyway. The NB is right next to and partially underneath the AGP card, and there's precious little clearance. I guess that's why they have the fan sunk into the heatsink. I was just lucky I had a nice fan that fit in there. If I didn't I probably would have used the one they supplied. But this works really well, as long as it keeps working. It's Taiwanese made, and on the fan it says "Hypro Bearing," whatever that means.

Since it's such a small fan, it could probably run on 5v just fine. So I wouldn't worry about killing it by undervolting.

Undervolting would really only kill a fan if you're supplying it with such a small voltage that it can't spin, but still high enough to cause it to heatup.

 

[Zepper]

http://www.buyextras.com has lots of unusual fans for chipset heatsinks, might find something quieter there. The size is 40x10mm and doesn't take enough current to power a flea... I think they have the exact one you mentioned there.Exact size but much more power - runs at over 10k rpm...

.bh.