Sunbeam Rheosmart 6 Fan Controller

[Syzygies]

I just completed a build using a Sunbeam Rheosmart 6 Fan Controller. (I'm about to start overclocking; the assembly is stable.)

I've convinced myself that I'm happy with the Rheosmart for now. There were however some quirks with my ASUS P8P67 Pro motherboard, that may be quite common. I'm posting my setup in hopes I might save others some time, or lead them to a different choice. This is a long read, but not if you're agonizing over this choice or trying to get it to work.

Mountain Mods Plateau 18 case
ASUS P8P67 Pro motherboard
Intel Core i7-2600K cpu
Noctua NH-D14 cooler
G.Skill Ripjaws 16 GB memory
MSI N460GTX Cyclone 1GD5/OC 1GB Graphics Card
9 Scythe S-Flex SFF21E 1200 rpm fans
1 Cooler Master Blade Master PWM 120mm Fan
ASUS DVD burner
Addonics Snap-In Double Drive
Intel SSD drive
Sunbeam Rheosmart 6 Fan Controller

This is a compute server, running Ubuntu, for math computations; the graphics card is for the 336 CUDA cores. Despite my misgivings about the Rheosmart, this build is virtually silent except when working at full load. In particular, only the graphics card fan and one cooler fan runs except when working, and I can't hear either of them over background noise.

I've come to love Mountain Mods cases, despite the cost. They're like renting a large, unfurnished apartment. I resent all the crap everyone else puts in cases, that just gets in my way. I picked a horizontal orientation this time, after seeing what heavy coolers can do to vertical motherboards without additional support. As a bonus, this case is more inviting to work on, either in place or by sliding out the motherboard assembly. The flagship MM cases would be twice as tall, leaving room for water cooling I'm not using. They're clearly aiming the Plateau case at yahoos, as there's no reset button. For now, I cross two wires like I'm stealing a car. The Plateau dimensions are arbitrary, chosen to be consistent with the rest of their product line, and slightly small for extreme cooling: I have to mount my three top fans outside the case to leave room for the Noctua NH-D14 cooler, and if one orders a 3-fan panel for the right side, there's no room for fans to fit inside next to the power supply and bay devices. I guess 10" by 19" by 18" doesn't have the same ring to it as 9" by 18" by 18". I'm quibbling; I've never had this much room in a mass-market case.

The memory is on the motherboard supported lists, and fits under the cooler. Addonics makes great stuff; this 2 x 2.5" trayless drive bay is more convenient than the 4 x 2.5" tray-based drive bay I've used before.

So what's up with the Rheosmart? The basic idea is that the front panel offers six 3-pin standard fan channels, each of which lets one choose between manual control with a dial (green LED), and using voltage control to follow the motherboard's PWM control of one fan (red LED). This makes sense, the motherboard has a better idea of the cpu temperature than any add-on fan controller could possibly have. I've built my share of DIY fan controllers (I'm partial to diode arrays) but I really want the fans to automatically ramp up when the CPU gets hot, and ramp down when the CPU cools off. My ASUS motherboard BIOS offers fine manual control of two 4-pin PWM fan headers, e.g. I'm now running 100% at 70 C CPU temp, 0% at 50 C, scaling in between.

Most of the reviews of the Rheosmart series could have been written without opening the box. They're all on those look-alike 17 page, ad-filled review sites, so no surprise. There are also Amazon and Newegg user reviews along the lines of "I installed it and my fans still work." There's an information gap here.

Motherboards vary in how they modulate fan headers. My ASUS in particular has no voltage modulation, only PWM, and needs to see a real PWM fan to function properly. In particular, the Rheosmart does not provide a sufficiently faithful simulation to fool the motherboard. One symptom (the first symptom I saw) was that the BIOS wouldn't retain custom manual fan control parameters until I attached an actual PWM fan.

The motherboard probably depends on the RPM signal for feedback; the Rheosmart doesn't let you choose which fan should be used for this signal, suggesting that it's not providing any RPM signal to the motherboard. Were it, say, defaulting to fan channel 1 for this signal, a warning to this effect would be nice, as I'm Y-splitting many of my channels, and that always confuses reading the RPM unless you snip one of the two RPM wires.

Sunbeam provides many cables; the most crucial cable splits a 4-pin PWM motherboard fan header into a 4-pin PWM fan out, and a copy of the PWM signals for the Rheosmart to follow. The documentation doesn't assert this, but one needs an actual PWM fan attached to the PWM fan out, for their whole rig to work. Otherwise, in my experience, it just runs full throttle. With the assortment of other cables, one can jury-rig returning the RPM signal from one of the analog fans, while reading the PWM signal from the fan header. At least, one can cable this. But it doesn't work.

After many experiments, I swapped the front 120mm 3-pin Noctua fan that came with the cooler for the Cooler Master Blade Master 4-pin PWM fan, attached it to the PWM splitter cable so the motherboard could directly see it, and the Rheosmart started functioning as advertised. PWM fans click, but I can't hear this one click once it's in place.

The Rheosmart more or less works. I used a voltmeter to check the analog fan output. (Sunbeam provides two 3-pin fan to 4-pin power converter cables, that are the right genders to allow monitoring their output with a voltmeter.) With the motherboard set to 0% (CPU below 50 C) the analog fans see around 1 volt, and don't run. The Cooler Master PWM fan continues to run at around 600 rpm; perhaps it defaults to a minimum speed with no PWM signal, while other fans would stop. In any case, I like this outcome. The Noctua NH-D14 cooler is perhaps overkill for a Sandy Bridge processor, but my rig sure is quiet in this mode.

As soon as one sets the floor PWM to 1% in the BIOS, the analog fans now see 10 to 11 volts, and run only marginally below their nominal 1200 rpm. Not ideal, but one can live with this: The fans come on for computations, turn off when they're done. This could be an artifact of my fan choices; with a different combination of the PWM fan and the 3-pin fans, the 1% voltage might be lower. But the point is, I can't adjust this on the fly.

I corresponded with mCubed over their FanAmp. It amplifies a 3-pin fan signal for many fans, and it can be tuned, unlike the Rheosmart. (Ideally, it takes two controls per channel, but I wish that the Rheosmart would at least have the dial adjust the floor voltage in PWM mode, leaving the ceiling voltage at 12 V. Instead, the dial goes numb in PWM mode.) mCubed claims that one can modify their amp for PWM use by cutting the red wire, and connecting it to the PWM wire. I haven't tried this, but I may.

Or one can go the DIY route. A trivial C-R circuit can smooth the PWM signal to a varying voltage, an op-amp can buffer the fan header from the output current draw, and a power amplifier can boost this to a range to drive all one's fans. A good beginner project. Ideally one has two such circuits, so some fans follow the CPU fan header, and some fans follow the chassis fan header.

What would be very slick would be to have all fans run at exactly the same RPM; there are chips intended for this, which one could smooth individually from PWM to voltage, allowing the use of a mixed collection of 3-pin fans. I wouldn't go to this much trouble for myself, but if I were entering the market in competition with Sunbeam, I'd do this. It probably doesn't matter for case fans, but I have heard out-of-sync push-pull cooler fans beat against each other. And "exactly the same RPM" is a good way to accomplish "roughly the same RPM" when using a mixed collection of fans.

One could also go the all-PWM fan route. The motherboard can't supply enough power, but there are cables that take power from a 4-pin power cable, and the PWM signal from the motherboard, to run many PWM fans.

I'm amazed at how quiet my fan-on-demand build is, using the Rheosmart, even if it was puzzling to get working. I give it a qualified recommendation, until someone does better. This shouldn't be long; adjustable PWM fan control is becoming the norm. There's the usual lag, where the 2600K doesn't need water but we know how to do water, the motherboard doesn't need an independent fan controller but look at all the independent fan controllers on the market, etc. It always pays to forget everything one knows and start over. Eventually various players in the market will do this.

Sunbeam Rheosmart 6 Fan Controller
Noctua NH-D14 120mm & 140mm SSO CPU Cooler
Mountain Mods Plateau 18
mCubed FanAmp Fan Controller
Cooler Master Blade Master PWM 120mm Fan
Addonics Snap-In Double Drive

 

[zagood]

Thanks for the review and personal experience, I've been looking at this since right before launch and now I'll know what I'm getting into.

 

[Binky]

In particular, the Rheosmart does not provide a sufficiently faithful simulation to fool the motherboard. One symptom (the first symptom I saw) was that the BIOS wouldn't retain custom manual fan control parameters until I attached an actual PWM fan.

I think this might need a little clarification. I'm pretty sure you're saying that the MB wouldn't save settings until you attached a fan to the Rheosmart. It would be pretty bad if the MB wouldn't save settings until you took it out of the loop completely.

It looks like an interesting device. If/when my IP35pro dies with its unbelievably good fan control, I might be looking into the Rheosmart.

 

[Syzygies]

I'm pretty sure you're saying that the MB wouldn't save settings until you attached a fan to the Rheosmart.

Yes, I'm saying that. YMMV.

My first try was to hook up the motherboard PWM out to the Rheosmart PWM in, then hook up all eleven case/cooler fans to the Rheosmart 3-pin fan outs. I used an RPM splitter to let the motherboard chassis fan header observe the RPM of one of the case fans.

I then selected manual control of the CPU fan, in the BIOS, and tried to change the default numbers (max temp and fan %, min temp and fan %). The choice of manual stuck (I was saving correctly) but the numbers themselves didn't stick.

While one can type in numbers, the manual is explicit that one adjusts them (+ or - 1 at a time) with the +, - keys. I haven't isolated whether this was the issue. Sounds preposterous, but not to someone who debugs other people's code.

Once I settled on the protocol of running a PWM fan from the splitter attached to the motherboard CPU fan header (bypassing the Rheosmart), and only using +, - keys to adjust the BIOS fan settings (I didn't isolate this, as at that point I was trying to get everything to work), everything worked.

There's an actual circuit in a PWM fan. When I instead tried to feed a different fan's RPM signal back to the motherboard CPU fan header, it didn't work. There's something about an actual PWM fan that I can't fake a la carte. Apparently, neither can Sunbeam.

 

[Syzygies]

Here are some more links, for anyone considering alternatives:

4-Wire Pulse Width Modulation (PWM) Controlled Fans Revision 1.3
Why and How to Control Fan Speed for Cooling Electronic Equipment

There are various standards for how a fan should respond to no PWM signal, including "run at lowest speed" as my fan does. Good luck establishing which standard a given fan follows, before purchase.

A PWM fan can be operated as low as 10% of full throttle, while with voltage control fans simply stop (and can have trouble restarting) at a higher percent. Modern PWM control operates at a frequency above the audible range. It might drive your dog crazy (a potential issue for me), but should be quieter than voltage control.

Perhaps I should embrace this now mature technology, and have all my fans be PWM?

akasa PWM Splitter - Smart Fan Cable
Molex 47053-1000 PWM fan header
Arctic Cooling 120mm PWM Fan (PWM Sharing Technology)

My motherboard can handle 1 amp on the cpu fan header; my PWM fans are 1/3 amp, so a two-way PWM splitter is fine for two cooler fans. (Be sure only one fan returns an RPM signal.) For more PWM fans, there are various cables like the akasa, which connect PWM and RPM wires to the motherboard fan header, but draw power separately from the power supply. One can easily make such a cable; the indicated PWM fan header can be used on a small circuit prototype board.

Although the PWM wire is just for signaling, there is a question of how many ways it can be successfully split. The Artic PWM fans have circuits to replicate the PWM signal in a daisy chain; in combination with the akasa PWM splitter one could apparently run 15 PWM fans off one header.

Alternatively, one could replicate the PWM signal using a small circuit, buffering it as one would use an op-amp to buffer a voltage control signal. I've seen references to this kind of circuit, but I don't understand them yet. The relevant Google keywords are PWM fan Schmitt.

 

[deimos3428]

I have one of these but my motherboard only lets me choose from "Silent", "Optimal" or "Performance" in PWM mode (or DC mode) so I can't fine-tune things all that much anyway.

I bought a couple F12 PWMs the other day to try out that feature, but I haven't played with them yet. My understanding is the controller can passthrough/replicate the PWM signal from a single PWM fan on the CPU header to other fans, but I haven't tested it out yet. The F12s can do that anyway, though, and do have a cable for returning RPM info.

It's a pretty good controller otherwise. It's not overly gaudy, though I do wish you could remove the LEDs outright...it's not like you can't hear if the fans are running.

Personally I like setting the fans manually in "happy" green-LED mode for surfing, etc. for silence, and have them running full out in "angry" red-LED mode for gaming with a quick flick across the 6 buttons. Having them continually auto-adjust based on heat would create a bit of an annoyance/distraction vs. a constant level of sound.

 

[Syzygies]

My understanding is the controller can passthrough/replicate the PWM signal from a single PWM fan on the CPU header to other fans, but I haven't tested it out yet.

The Rheosmart converts to voltage control. There's no way it can pass PWM without using 4-pin PWM fan headers for output. And in my case I observed a minimum voltage of 10 V, which is closer than I'd like to on/off control.

The F12s can do that anyway, though, and do have a cable for returning RPM info.

My understanding is that the motherboard PWM 4-pin fan header will automatically get RPM info. The separate RPM out on the F12 is there in case you want to share this RPM info elsewhere. It's optional.

Having them continually auto-adjust based on heat would create a bit of an annoyance/distraction vs. a constant level of sound.

Yep. Based on my experience with quad core Q6600's, I assumed that setting a floor CPU temperature of 50 C for my i7-2600K would cause all my fans to stay on for full throttle parallel computations on all cores. (With no PWM signal, my one PWM fan stays on low, and that's plenty for the Noctua NH-D14 cpu cooler at idle.) Instead, this is about where the top cpu temp settles (before overclocking) and the whole rig revs on and off like a teenager at a stop light. So adjust the threshold, or go to the green LEDs as you say. My nine Scythe S-Flex SFF21E fans on low are actually plenty of air for any operating condition. (Hmm. Then what' s the point of this thread? Good question, unless it's to say if you have nine case fans, don't bother with the Rheosmart.)

The advantage of moving to all PWM fans would be they'd scale smoothly, with no rev'ing on and off. Although the more I think about this, the better the mCubed FanAmp looks. If I can mod it for PWM operation, and set a floor of 5 volts for my case fans, I could achieve exactly the control I'm hoping for, that the Rheosmart fails to deliver.

 

[Syzygies]

I bought a couple F12 PWMs the other day to try out that feature, but I haven't played with them yet.

ARCTIC F PWM fan (PWM Sharing Technology)
ARCTIC F Pro PWM fan (PWM Sharing Technology)
Arctic Cooling 120mm PWM Fan (AcousticPC)
akasa PWM Splitter - Smart Fan Cable

From the AcousticPC product page for the Arctic F (not Pro):

PST: PWM amplifier integrated on motor circuit
4 pin plug for receiving power and PWM signal from motherboard
4 pin socket for CPU cooler or second fan
3 pin plug to send fan RPM signal to motherboard

Dimensions: 120 x 120 x 25mm
Rated Fan Speed: 400 - 1500 RPM
Air Flow: 56.3 CFM / 94.7 m3/h
Noise Level: 10.5 dB(A) - 24.5.0 dB(A), 0.05 Sone - 0.6 Sone
Power Consumption: 12 V, 0.13 Amp
Weight: 166 g
Bearing: Fluid Dynamic Bearing
Cable Length: 400 mm
Warranty: 6 Years manufacture

They state a daisy-chain limit of five fans. There is no separate power in, so the chain relies on motherboard power. At 0.13 amps, this is a total of 0.65 amps, which may be a conservative guess as to what motherboards can handle, for customers unwilling to do the math. My motherboard handles 1 amp.

The chain appears to be buffering and replicating the PWM signals. (There has to be something here to patent.) Such circuits can probably replicate the PWM signal down a far longer daisy-chain.

In combination with the separately powered akasa 3-way PWM splitter, I'm guessing that one can run more of these fans than anyone could possible need, off one motherboard header. However, I've written Arctic Cooling for advice.

If this works, the limitation to two models of fan (standard case for cooler compatibility, Pro for case fans) is a drag, but the result would probably be far superior to using the Rheosmart with analog fans, for all of the reasons discussed in this thread.

 

[Syzygies]

My understanding is that the motherboard PWM 4-pin fan header will automatically get RPM info. The separate RPM out on the F12 is there in case you want to share this RPM info elsewhere. It's optional.

Seemed like cable clutter at first, but I see the point now. The motherboard will see the RPM of one fan, presumably the first. Suppose that I provide separate power for my daisy-chain (e.g. the akasa cable) and arrange all eleven of my case and cooler fans in one chain, ignoring Arctic's advice to limit daisy-chains to five fans.

I don't need to borrow an oscilloscope, to see how degraded the PWM signal gets, at the end of the chain. If I can't hear anything wrong, and all the fans are running at roughly the same speed, then who cares?

Using the separate RPM monitoring cables, I can use the two free chassis fan headers on my motherboard to monitor the RPM anywhere on the daisy chain that I like. No extra equipment needed.

 

[kevindd992002]

Bump!

 

[Syzygies]

Not sure why the bump, but I wince now even thinking about this category of accessories.

Bottom Line: Do not buy anything in this category unless you know exactly how it is wired, and understand that it is wired as it should be wired. Do not be generous in making assumptions about products you do not understand.

* The Sunbeam Rheosmart 6 Fan Controller is not correctly propagating PWM control to all fans. It is faking PWM control using voltage control, which is markedly inferior.

* The Arctic Cooling (PWM Sharing Technology) fans are splitting a raw, unamplified PWM signal using a star wiring pattern that won't reach in many cases. They are not regenerating a fresh, clean PWM signal in a daisy chain. Star wiring pattern, not a daisy chain. They aren't providing auxiliary power, so motherboard header power limits apply. They might be using an op amp in each fan, or in some other way minimizing load on the PWM signal. If so, this is their only (barely) non-obvious contribution. I saw nothing to which I'd award a patent.

* Third-party PWM splitter cables may or may not inject auxiliary power, and may or may not return the RPM signal from one fan. To correctly permit a motherboard to control several PWM fans from a single header, the motherboard must see the RPM signal from precisely one fan. Inquire why you were sold an incorrectly wired PWM splitter cable, you'll get an answer that roughly paraphrases "we're morons selling to morons", or more generously, "The parts fit together and see power. What were you expecting?" Luckily, snip the right wire and such defective cables can be fixed.

If you're a manufacturer contemplating entering this category, the problem could be solved right, and no one has. If you want to blow away the competition, sell a front-panel controller that will take one motherboard PWM case fan header, and control up to 8 PWM case fans in lock step, exactly the same rpm as the motherboard believes one fan is running. This will be quieter, a major selling point, and RPM control is superior to voltage control. The chips for this already exist, you'll be assembling a standard circuit. You'll (of course) need to monitor the rpm from every fan, or else how will you know they're in lock step? And be generous in the number of headers, as headers can't be split further without losing the lock step.

Anyone else, my advice is to give the entire category a pass. Correctly wired 2-way PWM splitter cables can run two PWM fans off one motherboard header. If you have more fans than the motherboard headers can control, just set them to low somehow. With a decent case and contemporary cpus, the cooling bottleneck is the cpu cooler itself, where the motherboard can easily control a pair of PWM fans through a correctly wired PWM splitter cable.

 

[kevindd992002]

Alright. How about this PWM splitter: http://www.akasa.com.tw/update.php?...b=Fan%20Cable Adapters&model=AK-CBFA03-45 , this should be correctly wired right? It connects 5 headers with their PWM pins tied (in parallel) with each other, all +12V and GND tied also to each other, and one RPM pin for one of the fans. Will 5 fans draw enough "PWM signal current"?

 

[Syzygies]

Yes, that's a great cable. Some people wire it themselves, but why bother! It injects power, and the PWM signal splits five ways just fine.

Using five identical PWM fans, one will achieve roughly the same rpm in each fan, and PWM control has a much broader range than voltage control. So you're good to go. The Akasa cable is best-of-category.

 

[kevindd992002]

Right. What if I use 5 different fans, how would the PWM signal treat the fans? Will it base its computation solely on the fan with its RPM pin connected to the mobo?

Also, up to how many fans can you use when star connecting them?

 

[Syzygies]

Right. What if I use 5 different fans, how would the PWM signal treat the fans?

PWM is turning the power on and off quickly, in a square wave, these days at an inaudibly high frequency. Play around with which fan you choose to return the rpm signal. The motherboard will tune the PWM pulses to make that fan behave as expected, and the other fans will scale accordingly. They won't be at similar rpms. For example if you mix 1000 rpm and 2000 rpm fans, and tune using one of the 1000 rpm fans, then when the 1000 rpm fans are running 600 rpm, the 2000 rpm fans will be running faster. 1200 rpm would be a good first guess, but the situation isn't exactly linear without feedback which you don't have.

Also, up to how many fans can you use when star connecting them?

Anyone's guess, to be determined experimentally. Two akasa 5-way splitters, fed by a 2-way splitter? With injected power, it would be interesting to try.

Arctic Cooling states a limit of 5 fans. The Akasa cable also supports 5 fans. This suggests that Arctic Cooling is doing nothing novel, beyond what one sees studying their wiring pattern.

There are official specs for what a PWM fan must do. Each PWM fan has a tiny circuit inside, which reads the PWM signal. I didn't see in these specs any limits on the load this circuit is allowed to place on the PWM signal line. If they're all buying the same chip to use, it probably won't matter, brand to brand of fan.

If one can win the Indy 500 by finding a way to skip fuel pit stops, the analogous situation here would be to put the least load on the PWM line. With the least load, the PWM signal could be stretched to more fans. There are ways, such as op amps, to do this. I have no idea if anyone is actually worrying about this, but it shouldn't be patentable. You'd flunk first year EE if you couldn't figure out how to minimize this load as a homework assignment.

 

[kevindd992002]

What do you mean by "put the least load on the PWM line"? By load, my initial understanding was the number of fans, right? Then I read "with the least load, the PWM signal could be stretched to more fans". I'm not sure if I got that.

 

[Syzygies]

What do you mean by "put the least load on the PWM line"?

The PWM signal is a very weak on-off signal, telling the PWM fan when to turn on and off power to its fan motor. The actual motor power comes in on a different line, which is how e.g. Akasa cables can inject power.

It takes some work to turn the switch on and off. Perhaps you understand a mechanical relay? Enough power goes through one line to cause a magnet to hold two wires together, then lots of power can go through those wires. It still takes some power to hold the switch closed. If you had a weak signal line, it might not be strong enough to hold two relays closed at once.

Solid state electronics works the same way. If you split the PWM signal five ways, then one weak signal is trying to open and close five solid state switches. The power requirements per switch are much less than a mechanical relay, but there's still a potential issue.

In electronics, pretty much any problem is solvable if you're willing to throw in an extra circuit. Here, an op amp could buffer the input signal from the load required to throw each switch. They cost next to nothing, but these PWM fan circuits cost as close to next-to-nothing as they can manage, so they might leave out such a buffer as unnecessary.

In other words, if the design spec required that it be possible for a few hundred PWM fans to share the same PWM signal, it would be doable. Indeed, it would be easy, with the main issue being noise. However the design spec doesn't require this, and the PWM per-fan circuits are dirt cheap, so they could easily max out at five fans on a PWM signal, because each fan is hogging part of the signal to directly drive its on/off switch.

 

[kevindd992002]

Well, actually I do understand what you're saying since I'm an licensed Electronics Engineer in our country. I was just confused by the part when you said "with the least load, the PWM signal could be stretched to more fans" because for me least load = less fans, right? It seems to be contradicting in some ways for me but I'm sure I just didn't understand the point of the statement, hope you can clear that up for me.

 

[Syzygies]

If the PWM line can handle a load of "1" and each fan is a load of "0.2" then the system can handle five fans.

If the PWM line can handle a load of "1" and each fan is a load of "0.1" then the system can handle ten fans.

So if each fan is designed to be a light load, there's room for more fans. By "least load" I meant a PWM fan circuit design that imposes the least load on the PWM signal line.

My original point was to be sure one needs to worry about all this. For my overclocked Sandy Bridge cpu in a generous case, it's nice to PWM regulate a pair of cpu cooler fans, but the other fans really don't matter! As in, it does help to have them on, so the air changes inside the case every now and then, but turning them on loud makes only a marginal difference in overclocking range. Don't you have something else to worry about?

 

[dawp]

I have the rheosmart 3 and haven't seen any issues with mine. Works as advertised.

I did feed the rpm signal from the fan back to the pwm header on my motherboard. It did not run on auto until i did that.

I am not using a pwm fan. all my fans are 3 lead, not 4 and the motherboard does adjust the speed.

It's nice to cool a radiator, for benching and testing, set it hi and for running normally, set it to auto.

 

[Syzygies]

I have the rheosmart 3 and haven't seen any issues with mine. Works as advertised.

What is the minimum fan voltage that you see, with PWM set to 1%?

The Sunbeam Rheosmart 6 Fan Controller is not correctly propagating PWM control to all fans. It is faking PWM control using voltage control, which is markedly inferior.

Sunbeam Rheosmart 6 Fan Controller

Sunbeam does advertise that these controllers are designed for 3-pin fans. They don't say whether the control is analog or pulsed. I observed analog voltage control, with 1% PWM translating to a minimum voltage of 10 volts. Many of us apply voltages as low as 5 volts to 3-pin fans, for a much slower fan speed.

There may be some motherboards which are fooled by the RPM signal returned from the Sunbeam board; mine wasn't. Perhaps the Sunbeam board isn't even generating such a signal, which makes me wonder: Is its 4-pin fan header just idiot-proofing/documentation? This is likely, as there is no documentation stating which fan the Sunbeam board chooses to follow. So the board is either making an undocumented choice, or the classic mistake of returning all six signals combined, or is ignoring all six signals.

Like you, I had to use the additional cables and the RPM signal from an actual fan, to get my motherboard and the Sunbeam controller to play together at variable speeds.

So if a minimum analog voltage of 10 volts is acceptable, then yes, the Sunbeam controller does provide some measure of automatic control, "as advertised".

 

[deimos3428]

I've never gotten the PWM functionality to work with my motherboard (M4A78T-E), even with a PWM fan attached. I'm probably doing something wrong. But I don't really mind, as I didn't really buy it for that feature.

The Rheosmart 6 is still a sharp looking controller that allows me to adjust the speed of 6 fans manually, or switch them to 100% at the touch of a button. There aren't a lot of other 6-channel controllers in this price range, and in my opinion, none that look as good.

 

[kevindd992002]

Well, as for me I'm deciding to buy it mainly for the PWM feature. I have a sealed Lamptron FC5v2 with me (which is a sleek-looking fan controller, IMHO) but I can sacrifice that look if the PWM feature of the Rheosmart 6 works as "advertised". I'm disappointed that in the tests of Syzygies, it failed, knowing that his motherboard and mine (Asus P8Z68-V) is almost the same.

 

[deimos3428]

The more I think on it, the less I'm convinced you'd want a ton of fans on the same PWM signal, anyway. Two or maybe three, sure, but just doesn't make a whole lot of sense to tie all your case fans to one (CPU) temperature sensor.

Ideally you'd have multiple PWM fan headers and the ability to assign a temperature sensor for each, so that individual fans/groups could rev up and down based on the component they're cooling...but we're just not there yet.

 

[kevindd992002]

Yeah, but the thing is that the Rheosmart is designed to transform the 3-pin fans into virtually a 4-pin PWN fan which is just a great idea if implemented properly.