Do I really *need* a case fan?

jimmy · Post by **jimmy** » Sat Sep 08, 2007 10:49 pm

Hi there,

I've searched rigorously, and there doesn't seem to be a fan controller available which will actually turn off a case fan in certain scenarios.

I've been silencing my PC, which is doing very well (Intel core2 duo, Antec Phantom 500W PSU, Zalman 9500 CPU cooler, passive GPU, passive northbridge cooler, rubber mounted 80mm exhaust case fan @ 7V, suspended HDD), but since I have to sleep in the same room as the computer, I'd like it as quiet as absolutely possible.

As far as I figure, if the temp inside the case is below a certain threshold (eg 35C, maybe 40C), I don't see why the case fan needs to be on at all.
I'm thinking under normal loads (word processing, internet surfing, skype, downloading etc) that the case fan might not be required at all. Intel says you must have a case fan, but I suspect its only needed under load - especially since I have the huge zalman CPU cooler.

So, I'm thinking to make a fan controller based on a simple voltage switch (google "svs simple voltage controlled switch" and you'll see what I mean). Basically, I could then set the fan to turn on to +7V once the case temp reaches 40C, and it would turn off again once the temp dropped to around 35C (for hysteresis).

Obviously, the same idea could be used for additional case fans, so gamers could have a quiet system running 1 case fan normally, and once the temp increases, allow more fans to kick in. Or, it could be used for a front-of-case fan to cool HDD etc.

So, my direct questions:
1. Are there any commercially available fan controllers that already do this, so I don't have to solder one together myself?
2. At low load, is the case fan actually necessary anyway?
3. At what case temp do you think I should turn on the fan? Considering I live in Australia, ambient temperature can reach 40C... So I reckon 40C might be a good trigger point.
4. Where would be the best place to put the thermistor? I'm thinking right above the northbridge heatsink...
5. Other thoughts...?

Some requirements for this idea
- Needs to be fully automatic. I don't want to have to think about case temperatures, and switch things on and off myself...
- I want the fan to turn off. Just spinning slowly "almost silent" is not the aim, since I can already do that...
- I saw CPemma already designed a circuit for the switching, but it didn't seem that it had actually been built & tested, so thats why I went for the jaycar kit instead.

Das_Saunamies · Post by **Das_Saunamies** » Sun Sep 09, 2007 12:07 am

1. There is one such product I know of, and use: http://www.t-balancer.com/ (all the others lack features)
2. Intake you won't need, but I think the power-control components would appreciate it if there was some exhaust, especially with a passive PSU - they're hard at work even if there is little load.
3. Regarding starting temperatures you'd probably want to measure first and decide later. 40'C sounds low if it's hot at night.
4. The thermistor would get affected by any hot components in its vicinity. If you want ambient readings, the top of the case is the best bet, or the C-bar, and then make sure to keep it away from any heatsinks or spreaders. You could also let it hang free near the left side panel. If you want to measure component temperatures then the bases of heatsinks(GPU) or heatpipe junctions(9500 for example) are the best(easy installation, proper readings) places to do that - just make sure the fan doesn't interfere with the sensor. Measuring chipsets is a moot point as their cooling either works or fails, and processor temperatures respond with load better.

5. I'd swap the rear exhaust fan if possible. 120mm fans are even quieter than 80mm ones and still move more air, not to mention that the larger opening provides better exhaust by convection alone(also an opening for noise, but hardly an issue if not pointing directly at you). That's just about the only specification you mention, so further comments would be guessing. Measure your system, read the component specs and adjust accordingly, that's all there is to it.

I heartily recommend the T-Balancer. It's all the adjustment you'll ever need, even if it is pricey. I'm sure the Noisemagic chips will get mentioned sooner or later, but they just don't provide the same flexibility as a fully programmable controller.

thejamppa · Post by **thejamppa** » Sun Sep 09, 2007 12:27 am

Are you running your 9500 5v? If not that is probably loudest component you have. And since you have passive PSU, passive GPU etc you DO need case air flow or your components will get hot. Like Das_Saunamies said, 120mm exhaust would be idea. 120mm Nexus @ 7v would be almost inaudiable yet it would push nicely air.

blubberhoofd · Post by **blubberhoofd** » Sun Sep 09, 2007 1:52 am

hi,

how much fans you need depends largely on case and airflow design.

I've designed my AMD Semperon 2800+ desktop PC to run on only one fan, a 120mm Nexus fan @7V in the PSU.

The power output of your system is higher, so I couldn't recommend running on one fan alone.

Sounds to me like you could reduce to two fans by simply swapping your Case fan for a 120mm model and the CPU cooler to a tower heatsink, ducting the gaps between the heatsink, casefan and PSU.

Bluefront · Post by **Bluefront** » Sun Sep 09, 2007 2:30 am

T-Balancer.....too expensive for what you suggest/need.

Find a DigitalDoc 5-Plus. It fits in a 5.5" bay.....has an LCD screen, and comes with all needed cables and sensors. You can program a single fan (it can control eight) to turn on at a specific temperature......then turn off when the temperature drops slightly.

This device will not adjust fan speeds, so if you want the fan to run at a lower voltage, you'll need a Fanmate. These things are available various places....apparently no longer in production. I've found them as cheap as $15. The front bezel can be dyed to match your case, if you cannot find the right color.

This device needs no software.....all the adjustments are on the front. Excellent piece of hardware. Review

One more thing.....if you only want to control one fan, the rest of the cables unplug. You can still monitor eight temperature points, or just one and unplug the other sensors. Bonus....it's also a HD mount, although it has no fan. The earlier (non-plus model) version came with a small fan, and the temp warning buzzer had to be un-soldered. The "plus" version is a better choice....costs a little more.

Here's the early version for $13. I have two of these running.....orange back-lite, no front ports, buzzer needs to be unsoldered. The bad point of this version...the fan off point is only one degree below the on point. This makes the fan cycle too quickly, but can be worked around by correct sensor placement. The software CD contains only the manual on both versions.

Das_Saunamies · Post by **Das_Saunamies** » Sun Sep 09, 2007 3:29 am

The T-Balancer line is rather expensive, especially if it's just one fan we're talking about. But it is fully capable and adjustable, both of which will come in handy in a future upgrade.

I got one because it's the perfect solution, and since it's all the controller I'll ever need the investment will pay off in the long run. It already paid off as my cooling responds more closely to actual need now, and the PC is quiet even under load due to better balance - before I just cranked all fans to full as mechanical fine-tuning was tedious. If someone makes the perfect product for my purposes it would be madness not to take them up on the offer, and I encourage people to support such efforts when feasible. And really... 70 euros for something like the BigNG, it's what PC components cost!

But if this DigitalDoc can do what you need for that one fan, I'd go for it as the cheaper option.

--
One last point: software adjustment is more ergonomical(usually, as you just sit at your desk and insert values), more accurate(depending, usually you see a lot more data with software), and the T-Balancer only needs software for configuration. Once that's done, you can save your profile, close the program and never need to open it again. The process can be long(or short if you're experienced and lucky), but it's completely worth it.

Bluefront · Post by **Bluefront** » Sun Sep 09, 2007 4:06 am

These DigitalDoc units are cheap enough that I have used them as an eight-channel temperature monitor only......no fans hooked up. The unit can be cut apart and made to fit in two 3.5" bays (you'll need to make a new bezel).

And if you want an auto-fanspeed control, plug the DD5 into a NoiseMagic controller, rather than a fanmate. That way the fan can start turning at 40C, for instance, and after that be controlled by the NoiseMagic. That setup could cost <$30.

Das_Saunamies · Post by **Das_Saunamies** » Sun Sep 09, 2007 4:25 am

I do rate my time worth at least the 30 woolongs extra this controller cost me. No hack'n'slash, no tricks, just plug'n'play(after an hour of configuring it). It offers proper voltage monitoring, analog or PWM and... I don't think it lacks a single thing you could want from fan control unit.

It's a total solution out-of-the-box.

It's simply perfect, and I found my rants about no one making the perfect controller pretty silly after I tried it. I was drooling after the MFC2(probably 40-50 euros) when there's been this perfect solution available all along.

The only serious downside is how hard the mounting was. The backplate involves two screws in the wrong place and won't fit in many if any regular PC cases, and the 3,5" bay method assumes a standard screws-from-sides approach and is useless for the Sonata trays or any other non-neanderthal approach. In the end I just slapped the hideous velcro bits on and attached it to the bottom of my case.

jimmy · Post by **jimmy** » Sun Sep 09, 2007 6:49 am

Wow... excellent advice! Thank you!

I've looked up the t-balancer and it's certainly exactly the sort of thing I was looking for. But until you told me about it, I couldn't find it anywhere, despite hours of searching the net! (maybe I'm stupid...)

Since I'm an engineer, it looks like a good fun toy to me. At half the price, and a little fiddling tuning the potentiometers, the miniNG would probably suffice, but I'd love to play with the tunable side of things using the software. I am already starting to think that there's more you could do than fan control, just by using different sensors. Personalised computer gadgets could be possible

Thinking out aloud, a light sensitive diode could replace a thermistor, so when I turn the lights out to go to sleep, fans etc could turn off automatically! I could even control external devices using that voltage switcher with relay... oh, the possibilities!

The digitaldoc is also a nice solution. Only con is the front display, since I probably don't want my room lit up a nice blue color while I sleep, although it would be easily blocked. It seems there's a newer version than you have experienced - the buzzer is now switchable, and theres a couple of other nice features too.

Fan-wise, I would like to install a 120mm fan, but the back of my case is no where near big enough to replace the 80mm exhaust fan with a 120mm. From my reading, the best fan to have is a rear exhaust, so if I was to swap to a single 120mm mounted on the side panel, I'm not sure it would actually help - particularly since the 9500 is oriented such that its output faces straight at the exhaust fan right now.

However, I might look at undervolting the 9500. But I don't know how necessary it is, since it spins very slowly using the motherboard controller anyway, and I would hesitate to turn the cpu fan off altogether.

The PSU is passively cooled, with a fan that turns on if the temp gets too high. So, I figure that it will manage itself, and all I need to ensure is that the temp threshold for the case fan is below the trigger point of the PSU.

Any extra thoughts would be appreciated

Bluefront · Post by **Bluefront** » Sun Sep 09, 2007 7:59 am

The blue lite on the front of the DD5 can be turned off......on both versions. I have several of each version, so I'm aware of the differences. Both the DD5 and the NoiseMagic controllers use an analog voltage control, not PWM. There is no extra fan noise with either.

I usually put my DD5 in the top bay, and stuff all the extra power supply wires in the opening where a hard drive can be located.

I also have several M-Cubed products, including a mini-NG. Nice products......expensive, but nice. The DD5 is built just as well. The really big advantage of the DD5 over the t-balancer......it does not rely on a USB port, a USB recognotion, or any software. The thing is fully operational when the computer is turned on. You can change operating systems and the thing works exactly the same.

Das_Saunamies · Post by **Das_Saunamies** » Sun Sep 09, 2007 11:06 pm

Well, while you're at it... new, advanced case with proper fan slots?

It's true that the T-Balancer software doesn't work(or at least isn't supported) in Linux/Unix/Environment X, but that's rarely an issue. People usually find a way, even if that means dual-booting. You can even fit Windows installations on flash sticks or optical media if you are so inclined. I'm slightly surprised mCubed hasn't got at least primitive Linux support, as that would surely rake in a few more customers.

But yeah, the T-Balancers have great 'toy potential' if you know what you're doing, thanks to their full programmability. Even though it's just output that gets adjusted between 0-12V and input in either digital or analog form, that's all your basic electrical devices need.

Don't wax and wane too long now, choose what you need and get cracking while you've still got the spirit!

SilentKev · Post by **SilentKev** » Mon Sep 10, 2007 6:46 am

If a new case is out of the question:

Since the Zalman is pointed to the rear, remove the 80 mm rear fan and then make a duct to connect the 9500 to the rear opening. Then place a 120 mm on the side panel and add a foam lined duct on the outside of the case to direct the sound and case exhaust to the rear as well.

ronrem · Post by **ronrem** » Mon Sep 10, 2007 11:47 pm

Just because a Vid card and a PSU run fanless does not mean they are not putting out heat. Do you mount that PSU externally?

Likewise....a VERY good CPU cooler can pull heat up from the CPU to the fins,but those fins themn must transfer heat.

If its a hot day in Barstow and your car just sits there idling-and the fan is broken..you'll boil over soon unless your Radiator is 6 ft tall. You ACCUMULATE heat...and lack the airflow for all those fins to act as a heat exchanger. With a Puter in a case... you have a confined area less than 2 cubic feet....a space a 100 w lightbulb can heat up if there is no airflow.

Not just the CPU but the GPU,chipset,HDD's will build up heat.

A Core 2 is not an ultra cool CPU. A Sempron or bottom of the line Lima--undervolted to the max....CAN be cooled by only the PSU fan....in a system where that PSU fan is running at a steady 1000 rpm (at least) and where the case has a LOT of inlet area and is not too small and cramped.

A Via C7 or a Geode chip can run even cooler..but you still have heat sources-still need some regular airflow.

I've been looking at ways to use one of the 250 mm big fans at a very low rpm...350-500 rpm, as the only fan in a system. IF you have a WELL designed custom case....and mount that PSU outside or isolated from CPU/GPU heat.....MAYBE you could manage at under 500 rpm with a Big fan and a Core 2....especially if it used Crystal CPUID to dynamically undervolt and there was a "backup" 120 mm for when you were loading.

A 3600 X2 AMD may run cooler, the single core 65 nm Lima's should run quite cool and the low end Semps do run cool....as do some of the "mobile" chips. A COOL running CPU may let a big fan USUALLY run at 400 rpm or less.

Even with a fan near 10" diameter....it takes attention to detail -specifically airflow to do a one fan system.

If you are a machinist who can make heatpipes,heatsinks,it IS possible to do a NO fan computer. Otherwise---for big $ Zalman sell a case that a well planned rig can be done fanless.

jimmy · Post by **jimmy** » Tue Sep 11, 2007 5:57 am

Well my current plan is to get a t-balancer. Tomorrow I hop on a plane to go and live in Germany (very convenient that the t-balancer is a german product!). So once I'm on the ground and settled, I'm buying the t-balancer and having a play with it.

I'll let you know how I go, but my guess is that while the system is idling, it will dissipate enough heat using only the CPU fan. As far as I figure, old fanless CPU's *could* be used to run WinXP (slowly, but it is possible). So the power requirement can't be that big at idle. It's just when the core2 ramps up for some power computing that the cooling is needed.

I guess what I'm trying to achieve is to turn fans on only when needed. My biggest concern in my approach is overheating the HDD. All the other components only cost $$ to replace. The hard drive is a little more important. I'll probably create a sub-enclosure for the HDD within the case, so that the HDD temp is independent of everything else. Then I'll use the t-balancer to monitor HDD temps and turn on an extra fan if necessary.

Das_Saunamies · Post by **Das_Saunamies** » Tue Sep 11, 2007 8:21 am

HDDs can take the heat. What they can't take are variation in temperature, or sudden changes or stop-starts. Mechanical failure while operating is highly unlikely, usually what you'll get is a drive that refuses to boot one more time.

Good thing you're heading the product's way, I had to import it and that cost me a bit of extra. Hope you end up with what you want!

Also, a CPU cooler alone is pretty poor at keeping circulation going, even when blowing sideways. Exhaust fan is the priority.

Do I really need a case fan?

Do I really need a case fan?