This is an Intel G31 based system with a Celeron E3300 @ 2.9ghz. I already had the cpu, memory, and case, so I only needed a new PSU and motherboard to get it up and running. The OS is Windows 7 Professional. That is a Zotac board. Never used them before but it was the only choice I had at Microcenter with the G31 chipset and it was only 38 bucks! Not a great board with only VGA output and 10/100 ethernet. The plus side, however, is the solid caps and the nice build quality for such a cheap price. This system was designed to be low power with integrated graphics, one hard drive, and one DIMM. I just finished installing a Seasonic 300 watt PSU that is 80+ Bronze. There is 2 gb OCZ Reaper memory installed. The hard drive is a WD 250 gb I had laying around. Lastly, there is a sata Sony Optiarc DVD writer installed.

I recently switched over to the stock Intel cooler which is a 4 wire PWM fan. It is much quieter now with the stock fan. Also, I taped off the top opening with electrical tape and have a single Antec 120mm on low.

This system must seem lame to SPCRer's but hey, I'm just getting this one going now.

Three-wire fan != full speed.

Variable fan speed typically depends on the fan controller. Three wire fans require variable voltage. Four wire fans = PWM. On motherboards, sometimes only a few of the fan headers are variable. I had a AsRock AMD939 board where only the CPU fan header was variable. Check your BIOS - maybe there's a setting for dynamic fan control or something.

What's the model# of your Zotac board? Let's guess G31MAT-A-E?
Manual = http://downloads.zotac.com/mediadrivers/mb/man/pae4.pdf
See p. 36 "Fan Control" ... is smart fan control enabled?

If your NB is too hot to touch, plugging in you CPU fan may help. Since it's a top-down cooler, it might provide a bit of airflow over the NB heat sink.

So you are saying it's not "only full speed" if the board supports it? I guess I though only a 4 pin PWM fan could vary fan voltage, if I understood it correctly.

The model # is G31MAT-B-E. I don't know much about the motherboard fan headers and their capability to vary fan speed so I'm interested in learning.

Even if the board doesn't support it, you have options with a 3-wire fan. Three wire fans are simple things. Feed them less V and they slow down.

Generally, the three wire fans have red, black and yellow.
- Red = 12V DC
- Black = ground
- Yellow = RPM sense
The way to vary fan speed is to vary voltage.

A 4-wire means PWM = Pulse Width Modulation, and adjusts fan speed by adjusting the rate and duration of electrical pulses:
http://www.jmcproducts.com/products/pwm ... _faq.shtml

You'll notice that you can plug a 3-pin fan connector into a 4-pin motherboard fan header (the little plastic block is off-set).


OK. Then page 33 of this manual instead. Same principle - make sure your BIOS has smart fan control enabled. If smart fan control is enabled, and your motherboard still won't dynamically adjust fan speed, then try disabling smart fan control in BIOS and specifying the lowest fan speed availble in BIOS - see if the fan physically slows. If it doesn't, than I don't know - maybe your Zotac really can't do it with a 3-wire fan.

You could always hack it!
http://www.silentpcreview.com/article6-page1.html

Awesome!! Thanks so much for the info. I'll try here in a bit and post back if it works.

Also, I have to say, Zotac has one of the better Mfr. websites IMO. I give them alot of credit for that.

Jay, no luck with the CPU fan speed control so far. The bios default was on "quiet" and I changed it to "smart". I have not seen the fan speed slow down on either setting. Going back into the bios for another look. I'll report back.

Update: Set the fan speed on "Manual" and the minimum DEC number at 70. Still have not seen any varying fan speed, or any change from the same speed it is always on which is LOUD. Looks like either I'll have to switch to a PWM fan or passive hs. I haven't checked out the mod in Jay S's post above yet.

Just so we're not overlooking the obvious, you have the HSF plugged in correctly?


You want the circled pins. I would be amazed that a board couldn't control a 3-wire hsf.

I'm not trying to talk you out of going passive, but still - it's confusing why this isn't working.

Yes, it is plugged into the cpu fan header.

I'm not against using active cooling on the cpu, it just has to be QUIET as this thing will be running all the time in my bedroom.

What cpu cooler are you using

its basically the thermaltake version of this

http://www.newegg.com/Product/Product.a ... 6835150088

kind of a temporary solution until I figure out something better to get.

what do you guys think of http://www.newegg.com/Product/Product.a ... 6835108062 ??

FYI: Newer motherboards dont always support speed control on 3 pin fans. Known issue, and very silly tbh.

I've got an Asus AM2+ motherboard and the 3 pin fan header doesn't speed control , whereas the Gigabyte AM2+ motherboard I have does

Wow. That is ridiculous. I wonder if this is a hardware limitation or if a bios update could enable it?

To the OP - if you don't mind a little cutting, you can get 5V from any molex. See the link I posted earlier. 5V would take the HSF down more than 50%. Should be fine cooling your Celeron.

Take a look at Scythe cpu coolers. You get a lot of bang per buck with them.

Do you want a tower or a top down cooler?

Low end motherboards typically have limitations on fan control

probably top down.. considering the northbridge' need for some airflow.

Dumb question. Are you sure you have looked all over the bios control screens for an option that controls how the board handles fan control?

Check out this thread. That may be all you need to pick out a cheap top down. Linkcomputer had some cheap Noctuas and is mentioned there. But they are probably all gone by now.

http://www.silentpcreview.com/forums/vi ... highlight=

Also consider the Scythe Kabuto for an inexpensive top down that comes with a good fan.

I have been doing some research. It seems that the G31 chipset coupled with the ICH7 southbridge is about as low power as a 775 machine can get.

What kind of underclocking capabilities does this board have?

I can't find a list of approved memory for it. Is there such a list?

Was at the local Fry's yesterday and they had the MSI G31TM-P21+ Intel Celeron E3300 motherboard/CPU combo for $45 ($35 after $10MIR). It seems like a pretty good deal for someone building a low-power PC and doesn't need gigabit.

No idea what the undervolting options are but I think MSI has traditionally been pretty good in that respect.

haven't looked extremely thoroughly... been out of town for the last week so haven't been able to look at it.

Plus, the VGA output on this board looks God-Awful, so I'm kind of leaning towards getting a better card before I start using this machine much.

I'll take another look here and report back.

Between the mb and the cpu fan, it looks like my penny pinching is coming back to bite me in the behind... but at least these parts will make good spares