Silver Aluminum Rheobus w/Blue LED's

Date: 01.03.2002 




    Fan noise driving you crazy? Do you have to sleep in the same room as your PC? Well, you probably need a rheobus. While lots of 5 1/4" rheobuses have made an appearance from many companies, it's still kind of rare to find one that goes into a 3 1/2" bay now isn't it? Continue on as I take this somewhat hard to find 3.5" aluminum rheobus through the hoops. Don't forget to put your name in for the contest!



The Package:


    On first glance a nice little retail package is seen. Opening it up, we see the one page manual, the rheobus itself in bubble wrap, and a 4 pin Y adaptor so you don't lose a Molex connector. Nice touch actually. You'll even find four black mounting screws. So pretty much everything you will need is included.


(1) The package (2) The rheobus package (3) Included items



The Front and Back:


    One of the things I noticed, was that it is made of out one piece of aluminum. (The bezel and the sides.) The first thing I noticed however, is the knobs, which you can see better in picture 4. They look like someone had beaten them with a stick about 500 times! Ok, so I exaggerated, but it does detract from the over all look of the rheobus. Note: The knobs look to be made of aluminum, but they are really plastic. So I don't think you'll be able to do anything about the bumps on it. There is no way with the bubble wrap packaging that the rheobus came in, that it could have been beaten up in shipment. These do come all the way from Taiwan... Maybe I don't know what I am talking about. Either way, the knobs aren't terribly ugly, but this is a review. Would you rather have had me not mention it?


(4) The front (5) The back (6) And even closer



    You can see the shots of the backside of the rheobus above. And look ma, no cutting up fan wires! There are 4 pin adaptors on the rheobus! Thank you, thank you!



Light it UP!:


    A really neat feature of this rheobus is that the LED's on the rheobus change intensity going from high to low and vice versa. At a glance you can tell, if not hear what your fans are running. Even if you don't have a fan hooked up to the channel, it still works in that aspect. So how does this thing work? Well, look below. It is kind of hard to tell from the pictures, so I'll show off my mad imaging skills and make an animated Gif. (Picture 9) The camera wanted to take a bit more exposure than I wanted. I'll give you some details that you probably want to know next.


(7) Fans at high (8) Fans at low


(9) Animated Gif





    I'll begin this by giving you what to expect in voltage output to your fans. With the rheobus being on it's highest setting, of course you get the full 12 volts. With it on the lowest setting, 6.5 volts are supplied to your fan(s). Giving your fans almost half voltage really does make a huge difference. Below you can hear the 10 second clip of the fans running. They start out on high, then I turn them down. I wasn't able to clean up some of that background noise you hear, but by all means, if the mp3 was that horrible, I wouldn't have included it. Please right click on the picture, and select Save Target As...


(10) The sound file (mp3 - 104kb)



    So adding a rheobus definitely cuts down on the noise. Your case temperatures should be a bit higher then, but are you adding a another heater accidentally into your case? Huh?  This rheobus uses a variable resistor, so it will produce heat. I did some temperature readings. With the ambient room temperature of 24° C, I put a probe on the top of the rheobus. It was 33° C on the high setting. On the low setting, it was an astounding 40° C! While having good airflow inside your case will dissipate the heat coming from the rheobus fine, it is something to keep in mind.


    This rheobus supports up to 8 watts per channel. (A future version will support 13 watts.) Make sure you can look up, or know the fans wattage requirement. I put mine on a few 3 pin Y adapters that you can also get from AutoDeletePro in the 'Cables' section. So yes, you can put a couple fans, or perhaps one high flow fan, on each of the 4 channels if the need arises. I can actually hold 7 fans in my case. And I will be hooking them all up to the rheobus. You may also want to pick up some 3 pin extension cables too. None are included in the rheobus package. It would be pretty hard to run your fan cable from the back of your case to the front now wouldn't it?





    While this is my first experience with a rheobus, I'm certainly delighted. This is a good little unit. I can't say it is without flaws, but for money, this one isn't too bad. You should really be asking yourself, what is being able to sit by my computer without hearing whirring worth? This product does that. Some aesthetic issues I have with the knobs are justified, but it really doesn't detract too much from the overall look of the rheobus. I'm thinking unless you had a very brightly lit room, you really aren't going to notice it.




  • Fits in a 3.5" bay. Unlike lots of other ones that take up a 5.25" bay.

  • Variable brightness to the LED's while turning up or down the fans is a nice touch.

  • Inexpensive.

  • Will match your aluminum case.

  • Available in Silver, Black (13 watts per channel), or Blue brushed aluminum.


  • The fan knobs aren't quite as shiny as I would have liked to seen.

  • No extension cables, nor 3 pin Y adapters provided in rheobus kit.

  • Due to Variable Resistance instead of Pulse Width for controlling the voltages, the rheobus creates heat. 

"3.5 inches of fan controlling goodness!"


Date: 22.01.2003


Well where do I start?, after months of abating and begging Tigermain agreed to let me write a guest article on this quirky little rheobus. I have used various rheobus and baybus devices in the past to reduce the speed of the multitude of fans in my past projects – for both noise and cooling abilities.


The initial package that landed on my desk is tiny, the blue / purple box contains the Rheobus, Molex pass through cable, screws and the comprehensive instructions which state the specifications:-

  • 7v -12v
  • 8W per channel
  • 4 channels
  • 12v Molex input

The molex pass through is a nice touch, and Im sure 8W per channel is more than enough for even the most beastly of fans !

The box, stating product choice.

The contents with comprehensive instructions.

The Rheobus – showing how small it is.

Installation and Testing

Onto the good stuff - the installation and testing !! I decided to connect up various types of fans that would be used – an Enermax 120mm variable fan, a stock Intel heatsink fan, an Akasa blue LED fan and a Thermaltake temp variable fan – note that the connection for the fans is the standard 3 pin affair. I plugged in the molex connection and fired up the PC all the fans started up – as I had set the bus to max fan speed ( full clockwise turn) and in the process managed to take a chunk of skin from my thumb …

All hooked up. The fans are actually spinning – my camera is just so l33t ...


Mental note keep fingers away from spinning fans … invest in fan grills. The overall ability of this unit is good, however with the LED fan needed nearly all the 12v to start up, i.e. not much room for speed adjustment.

A better feature would have been a start feature where all fans have 12v fed to them when the pc is started up (like the Blacknoise version) as this would stop more powerful fans from failing to start. All the other fans they ran satisfactorily including the monster 120mm fan at the minimum level.

The rheobus comes in three flavours, silver black and blue aluminium. The brushed silver and blue coming with the obligatory blue LED’s and the black version with red backlights. The idea is the LED’s brighten when you increase the juice to the fans – in practice there is very little variation, but the back glow is reassuringly bright. The quality and workmanship cannot be criticised – all are professional made and put together well – the boards that all the components sit on is expertly soldered – it even has surface mount resistors.

I managed to pull off some of the aluminium knobs from the front to see if I could full dissemble the rheobus fully to no avail.

Daylight LED glow.

Night time LED glow.

Hmmmm can’t guess where this will go … new project alert!


After testing it to near destruction I am fairly impressed with the unit – it managed to handle the majority of the fans I have kicking around. The main plus points being the size – I have only ever seen 5 1/4 “ bay units – which to be honest don’t really need to take up that much space. The quality and workmanship is top notch, and is befitting a more expensive unit. The price is also very good, with competitor’s larger offerings being around the £40 - £50 pound mark. The downsides include the fact that it needs a large voltage to start some of the fans – leaving only a little room for adjustment, and the LED brightness doesn’t differ much from low to high voltage settings. The size could also be a problem if you have large fingers – the knobs could be classed as fiddly, but since I have small fingers it posed no problem.

Overall it is a useful piece of hardware to fit into your case – word of warning – never use this to control your CPU fan, as if the fan doesn’t start on boot you could be looking at a very hot and angry chip … and a large replacement bill.

     3.5' Rheobus
Ease of installation:
Total Rating:
8 1/4


PC Mods 3.5 Inch Rheobus

Date: 05.03.2003

With today's computer systems generating excessive heat due to the demands of the essential components and all of the peripherals, special attention needs to be paid to the dissipation of that heat. The PC Mods 3.5" Rheobus is one of many choices on the market today aimed at controlling both the cooling of your case as well as the noise associated with this important task. With so many choices out there for managing case cooling, what does the PC Mods 3.5" Rheobus bring to the table? The first thing you will note which sets the PC Mods 3.5" Rheobus apart from most other options, is its size... as the name implies, it is intended to be installed in a 3.5" drive bay whereas the majority of fan control solutions fit in a 5.25" drive bay.

The Basics:

A rheobus is simply a device that provides an array of rheostats, used in computer applications for controlling the speed of a fan. By turning the individual knobs on the rheobus, the resistance on each line is varied, which in turn varies the voltage supplied to the fan. This rheobus from PCMods provides an array of 4 rheostats, each of which can output 7-12 volts, with a maximum power rating of 8 Watts per channel .


Click image for larger view

The images above detail what you receive with your purchase. The rheobus arrives in the box pictured in the above left image, which includes all of the items pictured in the center image, as detailed in the list below:


  • The rheobus
  • 4-pin "Y" power adaptor
  • (4) mounting screws
  • Instruction sheet

As pictured in the above right image, the instruction sheet gives the basics of operation as well as some of the specifications of the rheobus (squint and you can just about read it).

Specifications (Taken from the PC Mods website and the included documentation):


  • 4 channel outputs - 8 Watts per channel
  • Fit in standard 3.5" bay
  • Blue LED back light around the knobs
  • Adjustable output voltages from 7V ~ 12V DC on each channel
  • The LED back light becomes brighter as the fan speed increases


Click image for larger view

Using the three pictures above as reference you can see that the body of the PCMods 3.5" Rheobus is constructed of brushed aluminum, with 4 chromed knobs attached for control. Each knob has a range of motion of about 3/4 of a turn, with a small dimple to indicate its position. Also note the ring around each knob, which may appear to be chrome in the above left image... This is actually translucent plastic, and when powered up, provides the blue back lighting mentioned in the specifications. The brushed aluminum of the housing looks great, but the quality of the knobs isn't as high, in my opinion. The finish isn't uniform, including dull spots and pits that take away from the looks of the device.

The sides of the rheobus include 3 mounting holes, as pictured above, which will allow you some flexibility when securing it to your case with the screws provided.

On the backside of the rheobus (pictured above right), you can see the electrical connections provided. Power is supplied to the rheobus via a 4-pin Molex connector, and then distributed to your 4 fans via (4) 3-pin fan connectors. The connections are laid out in an orderly manner and labeled for your convenience, and there are no electrical components mounted to the back side of the board which can be broken off by careless users. Some rheobuses have resistors or heatsinks precariously placed on the back side of the device just waiting to be accidentally pulled off by an entangled wire, etc.



The first step of the installation was to figure out how I was going to get power from the rheobus to my 4 fans. In the system where this is to be installed I have; (1) 120mm fan with a 4-pin power connector, (1) 80mm fan with a 4-pin power connector, (1) 70mm fan with a 3-pin power connector, (1) 50mm fan with a 3-pin power connector. The 70mm and 50mm fans will obviously connect to the rheobus with no problem, but the 120mm and 80mm fans required some modification in order to attach to the 3-pin power connectors provided.

You can buy adaptors to convert 4-pin fans to 3-pin, and vice versa, but I improvised with a cd audio connector and it worked just fine. My motherboards don't require the use of these 4 pin cd audio connectors any more, so I have a small pile of them just going to waste. By cutting one connector in half, I now had exactly what I needed. I spliced two wires from the cd audio connector onto my fan power leads, and then used the plastic connector to attach to the rheobus (see the below left picture).


Click image for larger view

Once the wiring to the fans was completed, the connection was made to my power supply unit, and the rheobus was slid into an open 3.5" bay. There were no problems with the physical installation at all. As pictured on the above right, the unit fit perfectly and the mounting holes in the rheobus lined up with the slots in my case to be secured with the (4) screws provided.

The two images below give a look at just how good the PC Mods 3.5" Rheobus looks installed in an AMS Electronics gTower all aluminum case.


Click image for larger view

The blue back lighting is more noticable than pictured above, but not overpowering either. Unlike some lighted rheobuses, this one supplies power to the lighting even when there are no devices connected to that particular channel. This is a nice feature if you're obsessed with symmetry (like me), and don't want to see one light out just because you are only using three of the four connections! As you adjust the rheobus knobs, the individual lights vary as well. The faster you set your fan, the brighter the light gets, giving you a general idea of your fan speeds with just a quick glance.

Two final looks at the completed installation...


Click image for larger view

This rheobus definitely looks good, but how does it perform? Controlling the fan speeds and the associated noise is the true purpose of the rheobus, so lets test it out...

Results & Conclusion:

For testing, I split the wiring on the installed 50mm fan so that the power was coming from the rheobus while the RPM sensing lead was connected to my motherboard. Using Motherboard Monitor 5 for RPM monitoring, I was then able to document the following speed outputs:

  • Max setting on the rheobus: 5714 RPM
  • Mid setting on the rheobus: 2926 RPM (Approx. 51% of max speed)
  • Min setting on the rheobus: 1714 RPM (Approx. 30% of max speed)

The range of speeds now available is helpful in making sure the components in my case are kept at an appropriate temperature while also giving my ears a break. That 50mm fan makes quite a whine at full speed, but even rolling it back to approximately 90% of full speed provides a substantial reduction in noise. As a second test I set my two case fans (the 120mm and the 80mm, neither of which has a RPM sensing lead) to roughly 80% of full speed, and was now actually able to hear the faint sound of my hard drives spinning. After 30 minutes at this 80% setting, Motherboard Monitor 5 did not report any increase in cpu or case temperature, and I enjoyed the new found silence.

With all of the fan control device on the market at this time, the PC Mods 3.5" Rheobus stands out as an option worthy of consideration. It does its job, and it looks good doing it. The price of $24.99 is reasonable, especially when compared to other 5.25" bay devices... with the added benefit of leaving your 5.25" bays free for other uses.

My only complaint on this device has nothing to do with its performance. As mentioned previously, the quality of the chroming on the knobs detracts from the overall appearance. Really not a major issue, and not noticable except upon a closer look at the device. Other than that, I would not recommend connecting more than one fan to each channel given the power rating of 8 Watts. Another rheobus I own has a power rating of 17 Watts per channel (and others available have ratings of 20 Watts per channel), meaning you can connect more than one device to each rheostat. That may be a nice feature to have, but not one that I require.



  • Fits 3.5" drive bay, leaving 5.25" bays available for other uses.
  • Very attractive, available in brushed aluminum or black finish.
  • Simple installation with or without enclosed documentation.
  • Reasonably priced at $24.99 US.



  • Lower total power rating than many other rheobuses.
  • Adapting to 3 pin power connections may be an issue for some users.
  • Quality of finish on knobs takes away from overall appearance.

Special thanks to PC Mods for providing their 3.5" Rheobus to I Am Not A Geek dot Com for review!

Added: March 5th 2003
Reviewer: Jason Kohrs (drfeelgood at iamnotageek dot com)


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Copyright © 2002 Øyvind Haugland
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