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Silence is golden

By Jon Wright. Published: 1st Dec 2003, 16:53:27 | Permalink | Printable

Knowing how to tell your RiscPC to shut it

The RiscPC may be officially out of production, but there's still many projects you can get your RiscPC involved in. Jon Wright talks us through how he silenced his noisy RiscPC to Iyonix levels. Disclaimer: This article assumes you're competent with metal based practical work and any modifications carried out on your kit is done entirely at your own risk.

Computers can either be a great help or a hindrance and can improve your concentration or be an awful distraction. As you may have guessed, the distraction I'm going to focus on is noise. This makes an interesting contrast to my last musings in which I was using a RiscPC to create as much noise as possible to entertain a pub full of beered up individuals.

Source of noise
There is nothing more irritating when you're sitting down trying to enjoy some, ahem, quality time with your computer than the constant noise it tends to produce. In modern AMD/Intel based PCs, there are all sorts of devices to ensure that the volume level rivals that of the reverse thrust of a Boeing 747. The most obvious one is the CPU fan - processors of the x86 family that are now running at 2GHz and higher do need some serious cooling. Graphics cards which flop out hundreds of terror monkey cycles per second contain processors in their own right and these also need fans to keep them cool. Some PC motherboards additionally need a fan on their internal chipset to prevent it from over-heating. We should be careful to not forget the PSU fan which is trying to keep the PSU cool as it pumps out large numbers of Watts to hungry peripherals. So, the PC is not only a noisy device but it is also a handy desktop hoover.

"Ah hah!" You may have just thought to yourself, "My RISC OS based machine uses a highly efficient ARM processor which requires no cooling at all!" Yes, that's right, and if you're the owner of an Iyonix, you'll note that they are barely audible over ambient room noise thanks to their quiet PSU fan, lack of a processor fan and a quiet hard drive. However, the Iyonix uses noise reduction techniques rather than noise removal techniques and as a result it is not silent in the true sense. In essence, to produce a totally silent computer, it should contain no moving parts at all (I will exclude the speaker from that sweeping statement).

Shut it!
What am I going to talk you through here is the way I shut my RiscPC up and turned it into a less obstructive machine that simply sits there patiently doing what I ask of it. I can't hear it grumbling and I'm sure it enjoys being up and running 24 hours a day even though it resides in the same room that I sleep in.

Learn from your siblings
I've always admired the A7000, not for its speed, but for the fact that it has always had something over its big brother, the RiscPC - a silent power supply! The A7000 case is also somewhat smaller than that of the RiscPC and can look tidier in the right settng. Have you worked out what I'm getting at? Yes, the first step in silencing the RiscPC was to transplant its motherboard into an A7000 case. Fortunately, the two motherboards are of a similar size although not all their screw holes are in the same place.

Removing the motherboards from each machine was relatively straightforward, requiring nothing more than a spanner for the peripheral connectors at the rear of the machines and a handy screwdriver.

Modification number one - Power supplies
Those of you familiar with the insides of the RiscPC and A7000 will know that they have different motherboard power connectors. After poking about for a bit with a multi-meter, I was able to work out that both PSUs output the same voltages on the same coloured wires. Connecting the A7000 PSU to the RiscPC motherboard was just a case of cutting the connector from the RiscPC PSU and wiring it up to the A7000 PSU, taking care to match the colours of the wires. At this point it was worth noting that the A7000 PSU has a much lower power output than that of the RiscPC and as a result would not be able to run with too many peripherals before struggling.

Modification number two - StrongARM daughter card
The RiscPC motherboard was never designed to go inside an A7000 case and as a result, I found that the StrongARM card was in the way of the A7000's metal chassis. I could have solved this problem with a 90degree StrongARM mounting connector but these appear to no longer be on sale from Castle. In protest, I pulled a hacksaw and file out of my back pocket and proceeded to attack the metal after marking out where the spatial conflict occurred with a pencil.

With my knuckles safely nestled in some plasters and the RiscPC motherboard safely nestled inside the A7000 case, it was time to turn my attention to the only remaining source of noise; the hard disc drive. As you know, RISC OS has never been that heavy on data storage requirements. Most RISC OS applications weigh in at under a megabyte and have difficulty even filling up a small (by today's standards) 40 gigabyte hard drive. After some research, I decided that the best way forward was to utilise the CompactFlash storage format; it has no moving parts and a 256MB card is relatively cheap and would be more than enough for all my RISC OS applications and current data requirements. Should more be required, then my server would be able to provide storage space via NFS with Sunfish using the RiscPC's installed network card.

Naturally, there is no CompactFlash connector anywhere on a RiscPC motherboard but it is possible to buy a hardware interface which will make a CompactFlash card look like a normal ATA hard drive to the host computer. This part of the silencing operation was so easy, it only required me to plug it all together and switch on. From this point I was able to format the CompactFlash card using !HForm as though it were a normal hard drive and then copy anything I required to it.

Living with silence
My RiscPC is now able to play me quiet music that I can drift off to sleep with, not even a trace of a whining fan noise in the background. I can leave it on all day and night without it bothering me and with a ready-to-use time of zero seconds.

The CompactFlash card is not as quick as a hard drive, certainly the transfer rate is under a megabyte per second but thanks to the low memory requirements of RISC OS, this is rarely noticeable (just load all your applications at startup).

Due to the low power output of the PSU, I do not overload it with peripherals. This would be difficult anyhow due to the limited expandability of the A7000 case which can only take one expansion card. I have settled on a ViewFinder card to fill this hole although I do sometimes wish I had the room for another podule for video digitising. Still, this would be in reach if I moved the motherboard and PSU back into a RiscPC case.

I've not looked back since doing this modification and in my mind it suits RISC OS perfectly, allowing me to unobtrusively get on with the task in hand.


CompactFlash card in IDE interface

RiscPC in an A7000

RiscPC motherboard

Cut out required to get the card to fit

PSU re-wiring


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I did this myself once - but in a more trivial way. I went to Maplin and bought a replacement fan for the PSU that was extremely quiet for about a fiver. Then I used a modern Maxtor hard drive which are so quite once they're spun up you wonder if they're still spinning. Job done. :)

 is a RISC OS Usernunfetishist on 1/12/03 4:57PM
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Care to quote part numbers?


Nice mod. The only things holding me back from doing the same is my need for a 4GB drive and the lack of an A7k case :)

-- Spriteman

 is a RISC OS UserSpriteman on 1/12/03 5:23PM
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Spriteman> You can pick up an A7000 case for less than 30 pounds on ebay if you look around.

If you have no need for a floppy drive or CDROM drive, you can pop a silent hard drive in those positions.

 is a RISC OS Userjonix on 1/12/03 5:40PM
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Spriteman: It was quite a while ago - I don't recall. jonix: Tsk, not silent, just very quiet. :)

 is a RISC OS Usernunfetishist on 1/12/03 6:50PM
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My RiscPC, "oxster", is stuffed in the cupboard of my desk. I also dislike the noise of the fan and it doesn't seem to get too hot in there. Not sure if my wife would let me have even a silent computer in the bedroom though !

 is a RISC OS Usermartin on 1/12/03 7:34PM
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I think the noisiest part of my RiscPC is the VRAM, whining away when you move a window. Viewfinder2 remedied that! ;)

 is a RISC OS Usersimo on 1/12/03 8:51PM
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> I think the noisiest part of my RiscPC is the VRAM

I think it's actually the PSU that whines, in response to high frequency noise on the supply lines.

I once overclocked my StrongARM and it worked perfectly but the whining/whistling annoyed me so I put it back. You could actually hear when the CPU was spinning; an interesting way to debug programs.


 is a RISC OS Useradrianl on 1/12/03 9:32PM
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Cool B-)

Mine makes a noise as I move the mouse over different icons on the screen. If you listen closely then you can even hear graphics calculators and digital watches whine (especially just after replacing the battery) :-o

 is a RISC OS UserPhlamethrower on 1/12/03 9:40PM
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Why do I associate the noise with Acorn computers? My A310 does it, as do all of my RPCs, yet I've never heard the noise from a PC before.

 is a RISC OS Userfylfot on 1/12/03 9:49PM
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Proabably because PC fans are too noisy and drown it all out

 is a RISC OS UserPhlamethrower on 1/12/03 10:14PM
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fylfot: My PC randomly outputs the noises on the speakers for me when I move things around etc :)

 is a RISC OS Userandypoole on 1/12/03 11:04PM
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> Why do I associate the noise with Acorn computers?

Perhaps because when the CPU is idling it's executing a few instructions (to check mouse movement/clicks etc) over and over... with RISC OS being so much simpler than other OSes, and being written in assembler, you have a shorter loop (hence higher frequencies) and it has a more obvious periodicity (more tonal rather than white noise).

I've heard of engineers on older computers using this sort of side-effect to debug code - really! In fact I've done something similar myself a couple of times.

You're not a true geek until you've debugged your software using an oscilloscope and/or logic analyzer! :-)


 is a RISC OS Useradrianl on 1/12/03 11:15PM
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Of course, one of the original programs for the Altair computer, which had no display, just two rows of 8 switches, and a "store" button, and a load of LEDs, was something that when you placed an AM radio near it, played a tune via it.

 is a RISC OS Usernunfetishist on 1/12/03 11:56PM
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I'd love to silence the PSU on my RiscPC - it's got very loud nowadays - as loud as my old PC with 7200rpm CPU fan and PSU fan! This strikes me as a Bad Thing. How hard is it to silence a RiscPC's PSU? Is the fan easily replaceable? Can I plug a new PSU in, even?

 is a RISC OS Userjohnpettigrew on 2/12/03 9:29AM
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johnpettigew> As nunfetishist mentioned, you can remove and replace the PSU fan but beware if you're going to do this yourself because a PSU can contain high voltages even when it's turned off. Alternatively, you could fit an A7000 PSU providing your demand on peripherals is not too high.

 is a RISC OS Userjonix on 2/12/03 10:10AM
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johnpettigew: Fitting a new fan isn't difficult, but you have to be careful for the reasons Jonix stated. Why Acorn didn't use an off-the-shelf PSU is beyond me! It would have been a lot cheaper.

 is a RISC OS Usernunfetishist on 2/12/03 11:47AM
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One other thing worth noting is that if your fan is getting noisier then a drop of 3-in-1 oil can sort it out.

-- Spriteman

 is a RISC OS UserSpriteman on 2/12/03 1:17PM
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another option if you are confident within the PSU is to fit thermostats (sort of like iyonix) - there is plenty on the PC market which, if you are willing/capable, can be used to silence the fan.

however do not forget that the fan in a RiscPC is not just for the PSU...

 is a RISC OS Userepistaxsis@work on 2/12/03 7:17PM
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A few years ago I simply removed the fan from my RiscPC PSU and replaced the HDD with a CF card. It has worked perfectly without a single fan for several years now.

 is a RISC OS UserJGZimmerle on 4/12/03 8:39PM
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My RiscPC makes strange noises over FM ;^) every time I move a window.

 is a RISC OS Userem2ac on 8/12/03 12:03PM
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The iiyama 514 they swapped me for the previous 512 is much better, but it does hum consideravly, and changes pitch when the optical mouse plugged in to its hub is moved and switches to full beam.

Its ok with the Iyonix on (now I replaced the whiny disc), and ofcourse is completely drowned out when I turn Risc PC noise box.

 is a RISC OS Userdruck on 28/12/03 10:35PM
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could someone point us to the CF-IDE interface partnumber/supplier?

 is a RISC OS UserRien on 7/8/04 5:56PM
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