case fans power and control

[fasdl]

Hi, I'm getting a case with a side 250mm fan (enermax chakra) which can be used as intake. And want to use the front and rear 120mm optional mounts as exhausts. I have never built a computer before and don't have any recent machine to compare it to.
Need some pretty good cooling, going to SLI 2 8800gts and be using Foxconn N68S7AA (680i chipset) with e6600 at about 3.0

As I understand it case fans are either always on full power, hooked to some sort of fan controller, or somehow hooked into a power supply controlled by the motherboard or connector motherboard itself.

I've read something about fans having some kind of tachometer that reports speed and is controlled by software or bios. This is what I would like, to have it be something I can control and be automated by system demands or custom thresholds. I think this is possible right? correct me if I'm wrong.

So basically wondering what type of fan and connector or power setup I need to do this. From reading on newegg it appears not the most straightforward thing. People are posting things about how the fan didn't have the right connector hook up to mobo, another site with powerful fans warns connecting to the mobo will draw too much power and harm it. (http://www.xoxide.com/120mm-nidec-fan.html) It says it's 5.8w max but I've seen 6w fans with no such warning. And then there is all this stuff about 3 and 4 pins, different voltages, and some which are 'Molex'.


If I have case fans though, how will my system control them all if there is only 1 hookup on mobo? Or does the mobo regulate the power to the power supply that controls the fans? Ok, I'm lost, Understanding case fans is so much harder than I thought!

To summarize: I just want some fairly high cfm fans and a way I can control using my system. If this is impossible I'll just get fan controller.

Thanks!

 

[zagood]

1. To control fans via motherboard, all fans have to be hooked to the motherboard. Sounds stupid, but yeah, good info. You could conceivably mod fan wires to run more than one fan on the motherboard, but wouldn't recommend it.

2. To run fans at a consistently slower speed (but having no control) you can either mod 4-pin molex fans that plug into the power supply like so:
http://www.silentpcreview.com/article6-page1.html

or you can get an inline resistor (or some other sort of voltage reducer) for 3-pin plugs like so:
http://svc.com/zamuco1z.html

3. To control via software, another choice is the Sunbeam Theta. It's a card that plugs into a PCI slot (but also USB) that you can set through windows.
http://www.performance-pcs.com/catalog/...ain_page=product_info&products_id=4026

4. The old standby, and my favorite, mount a fan controller. Sunbeam Rheobus is the classic.
http://jab-tech.com/Fan-Speed-Control-c-42.html

5. To avoid confusion...4-pin molex is like the plug that goes into a hard drive or DVD burner...there is also a new(ish) 4-pin motherboard fan connector that's used primarily by heatsink fans. You can connect 3-pin fan connectors to these with no problem.

-z

 

[Eirgorn]

Can I ask some newb questions for clarification?

1) Any fans that you power directly from the molex connectors from the PSU an dnot though the fan controllers on the mobo will always run at factory speeds (not voltage mods used of course).

2) For my board in particular (been setting it up this afternoon, just have to wait until Monday for my GPU) the fan connectors I see are the:

a) CPU_FAN - which I have my CPU fan (stock) connected to
b) NB_FAN - which I dont have anything connected to (stock NB heatsink - no fan)
c) PWR_FAN - which I dont have anything connected to - but I assume if you used this you could control fan speed via the mobo?


Right now I just have one 80mm fan mounted in the bottom front of my case hooked straight the a 4pin molex connector and Im waiting on a 120mm to put in the rear of the case. Should I just put the 120mm straight to the PSU or run it through the PWR_FAN?

Are there any dumb things Im missing?

Thanks a ton!

 

[Binky]

1) Yes

2) Either power source will work fine. If you use the motherboard connectors, you may be able to control the speed within windows. See if Speedfan can control one or more of your motherboard fan connectors. Some motherboards can't control any of the connectors, some can control the CPU only (most likely), and some can control more than one.

Speedfan can also read the speed of any fans connected to your motherboard connectors.

 

[Eirgorn]

Thanks for the info Binky!!

I'll DL Speedfan on Monday when I get the system up and running (along with all the other benchmarking/OC software) and see what all it will let me take care of and just try different things.

 

[fasdl]

Hey I finally figured out how to rig my fans and have considered everything from rpm monitoring to this advanced controller device called a Alphacool T-Balancer bigNG. The software controlled Theta is a fascinating and unique device but has been seen more as a gimmick than anything else.

Question here about how much power can come out through PWR_FAN? If it's chip controlled voltage regulated it may have a low tolerance, likely 10w. This is no problem with some weaker fans, I can actually hook them all up to the one 3 pin out using splitters. I'm just wondering how much is safe to pull and what if I do something wrong and short it? Does it just have a cut off or will it fry from too much draw? Anyway I probably consider myself pretty well educated on these fans now.

Part of the confusion was from the first fans I looked at were the Silverstone fm121 which insist upon using their own proprietary 2 pin controller and intake or you must use the always on 4 pin input passthrough.

I'll probably test a few setups and see what I like.

 

[WoodButcher]

Originally posted by: fasdl
Hey I finally figured out how to rig my fans and have considered everything from rpm monitoring to this advanced controller device called a Alphacool T-Balancer bigNG. The software controlled Theta is a fascinating and unique device but has been seen more as a gimmick than anything else.

Question here about how much power can come out through PWR_FAN? If it's chip controlled voltage regulated it may have a low tolerance, likely 10w. This is no problem with some weaker fans, I can actually hook them all up to the one 3 pin out using splitters. I'm just wondering how much is safe to pull and what if I do something wrong and short it? Does it just have a cut off or will it fry from too much draw? Anyway I probably consider myself pretty well educated on these fans now.

Part of the confusion was from the first fans I looked at were the Silverstone fm121 which insist upon using their own proprietary 2 pin controller and intake or you must use the always on 4 pin input passthrough.

I'll probably test a few setups and see what I like.

A splitter off the mobo? no.
If you want to play with splitters use a pass thru direct to the psu or on the sunbeam that zagood mentioned earlier. If you were to connect to the mobo you risk damage to your entire system. Granted to lose the foxconn would not be a great loss but that 6600 is a nice chip.

 

[fasdl]

ok thanks, I'll steer clear of that!

 

[WoodButcher]

Post how that foxconn is, specifically the bios fos overclocking, I need a MATX that will run the 840 extreme and foxconn is one of a very few who make a matx board for that chip.