I believe it´s a waste of money, and time, to put  high, or even low,  end hardware in a  (EMR) noisy enviroment, so I´ve extracted from an "old" AMD paper (Builder’s Guide for AMD Athlon™ 64 Processor-Based Desktops and Workstations) 8 tips that maybe can help choosing and setting up cases and motherboards, from a pc audio play back standpoint.  I think it would be interesting to get people feedback on this matter, now that many question the effectiveness of dedicated sound cards:
 
 
 
[size=medium][size=x-large]5.2 AMD Athlon™ 64 Processor-Based System Builder EMI Reduction Techniques [/size][/size]
[size=medium][size=x-large][size=11.5pt]This document describes system-level EMI reduction techniques based on past successful problem resolution of EMI radiated emissions. All the techniques described may be able to be implemented at the final system assembly stage with relatively short lead-time. This document does not contain long lead-time techniques involving motherboard re-layout or chassis sheet metal redesign. Proper up-front electromagnetic compatibility (EMC) motherboard design techniques are assumed. For more information on these techniques, please refer to the [/size][size=11.5pt]AMD Athlon™ 64 FX and AMD Opteron™ Processors Motherboard Design Guide[/size][size=11.5pt], order# 25180. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]The effectiveness of the following EMI reduction techniques varies among different computer systems. EMC engineering tests must be performed to determine how effective each of the following EMI reduction techniques is for a particular system. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]The following list of EMI reduction techniques is numbered in the recommended order of evaluation and relative simplicity. Each item is described in detail for clarity. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]1. Spread Spectrum Clocking [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]AMD processors are designed to run with spread spectrum clocking enabled. Ensure that the motherboard BIOS has enabled the spread spectrum feature of the system clock generator. Enabling the spread spectrum setting often lowers frequency amplitudes by more that 5 dB. [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]2. Disable Unused Clocks [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]Clock signals that have no load can have high levels of ringing that can lead to EMI problems. The motherboard BIOS firmware should be programmed to detect and disable unused memory DIMM and PCI clocks. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]3. Processor Heatsink Fan Cable Routing [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]A problem sometimes encountered with the processor heatsink DC fan cable is the large loop formed in its routing to the motherboard connector. Shorten this cable length to reduce the loop area as much as possible. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]4. Power Supply Cable Routing [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]Historically, the system power supply cable has been found to be very susceptible to picking up EMI energy from within the system and coupling into the power supply and then onto the AC power cord. Keep the power supply cable against the metal chassis and as far away from the processor, memory DIMMs, and VRM components as possible. Fix this cable routing in place with plastic cable ties. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]5. Other Internal Cable Routing [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]Cable routing inside the system should generally be routed along the metal chassis and away from EMI sources such as the processor heatsink, clock modules, memory DIMMS, VRM components, and high speed VLSI modules. Internal cables that connect to front I/O ports such as USB and Audio are particularly sensitive. The use of a shielded cable or a ferrite core or both over these internal cables can be effective at reducing EMI. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]6. Rear I/O Connector Shield [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]One common problem in many computer systems is poor electrical contact between the I/O connector metal housings, the metal I/O connector plate, and the cut out in the system chassis wall. This problem can be due to soft metal being used in the I/O connector plate or to an insufficient number of spring-finger contacts. A solution is to use a hardened stainless spring steel with a sufficient number of contact points to the I/O connectors and the wall of the system chassis. Each I/O connector housing should have at least two contacts and as a general rule, there should be a contact point at least every 1 cm between the I/O connector plate and the chassis. As a quick remedy if this condition exists, a die-cut, conductive, foam gasket matching the I/O connector pattern can be added to improve connector grounding to the chassis. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]7. Chassis Shielding [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]All chassis designs have gaps and seams to enable assembly and option installation. From an EMI standpoint, however, some gaps are worse than others. The important dimension of a gap or seam is the longest dimension. If you can slide a piece of paper for several inches along a seam, that [/size][size=11.5pt]seam could cause an EMI problem. Spring fingers or foam EMI gasket can be used to seal these gaps or seams. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]8. Processor Heatsink Grounding [/size][/size][/size]
 
[size=medium][size=x-large][size=11.5pt]Although grounding of the processor heatsink has not yet been required on any AMD Athlon™ 64 processor-based systems, grounding of the processor heatsink can further lower the harmonic EMI levels of the processor. Many AMD Athlon 64 processor-based motherboards contain grounding pads around the footprint area of the processor. These grounding pads can be utilized to ground the heatsink to the motherboard ground. [/size][/size][/size]
[size=medium][size=x-large][size=11.5pt]If excessive system level EMI radiated emissions exist after attempting all the listed EMI reduction techniques, then more extensive remedies may be necessary. First, determine if the emissions emanate from the system I/O cables (including the AC power cord) or from aperture leaks in the system chassis. If EMI emissions emanate from a particular I/O cable, then improved filtering or cable shielding may be required on that cable. If EMI emissions emanate from slots or seams in the chassis enclosure, use copper tape across the apertures to improve shielding effectiveness. If copper tape reduces emission levels to a satisfactory level, then chassis sheet metal changes or conductive EMI gasketing can be added at that location. [/size][/size][/size]
 

That's an interesting read. It's long been known that PC's are terrible for audio because their so EMI noisy.  I've noticed over the last few years that some of the more expensive soundcards now come with an electro-magnetic shield fitted around them which must help alot.
 
EMI only effects analog signals so the best way is to use a digital output (optical or USB) to get the audio signal away from the EMI noisy innards of the PC. You can then use an external DAC to convert the digital signal to an analog signal at a safe distance from the PC without risking any EMI.
 
 
Here's a pic of a soundcard with an EMI shield if anyone's interested
 

 

I've always found this interesting. Just curious how someone would go about determining the amount of EMI in a setup, and where exactly it emanates from. A meter in proximity? An integrated/inline detector? Step by step replacement of things to see how the result changes? It would be great to hear a recording or see a chart/graph demonstrating the difference in the final resulting output ( Music ). I wonder if there is something like that around. I've always thought that people don't give this EMI much stuff as much thought as they should. Of course in this aspect you would be considering signal degradation, but there are also health effects like a lot of those lexan/plexi side windows in my opinion.  There's a good book called Dirty Electricity may be of interest for health effects, but we are surrounded by the stuff. I got rid of all my wireless stuff for that reason, but back to the topic I'm rambling.  How would all this stuff be determined? I could ask at work maybe see what the guys who deal with this stuff say, but they probably don't care or give it much thought. See what happens.
 
I know that apparently the newer Gigabyte boards are supposed to have lower EMI due to the design ( UD3 and up ) at least that's what I heard somewhere. Thats what I grabbed.
Looking forward to further info.
 
 
yay 100th post !

 
Quote:

nick n said:

I've always found this interesting. Just curious how someone would go about determining the amount of EMI in a setup, and where exactly it emanates from.
 

Click to expand...

Please understand that I'm no expert on the subject of EMI so this reply is based on what I understand about basic science and may not be totally accurate.
 
Depending on its frequency/wavelength the electro-magnetic spectrum ranges from gamma rays to X-rays to ultraviolet light to visible light to infrared light to microwaves and radio waves. Most people don't seem to realize that all of these things are exactly the same apart from their wavelengths. Now I'm only guessing here, but I think that the electro-magnetic energy given off by PC components is in the frequency range of radio waves. So you should be able to test how much EMI a PC has using a regular radio receiver with an Ariel. By listening to the sound (or measuring the signal) the radio receives from the PC you could tell how much EMI it is transmitting.  Also by adjusting the tuning on the radio you could measure how much EMI is being transmitted at different frequencies (wavelengths)
 
However I strongly recommend that you DO NOT TRY THIS YOURSELF because you will risk getting killed by electrocution if you poke a metal ariel inside your PC while it's turned on!  You would also risk damaging your computer by causing a short circuit.

I wonder if we could use the  8 tips above, and others too,  to choose the  hardware;  motherboard, processor, psu, etc,  to set up the best rig, from audio quality stand point.  Just to exemplify: Here, http://www98.griffith.edu.au/dspace/bitstream/10072/13779/1/40559.pdf,  is a paper investigating the "new" grounded heatsink for the P4 (not to mention the Gigabyte UD3 and the shielded SB above) .  
A case built according these 8 specs would be great !

 
Quote:

nagual said:

I wonder if we could use the  8 tips above, and others too,  to choose the  hardware;  motherboard, processor, psu, etc,  to set up the best rig, from audio quality stand point. 

Click to expand...

PC's that deliver genuine hifi quality audio already exist but they're very expensive.  They are marketed as media center PC's for home cinema use and can be used as an audiophile quality music server.  If you check out the websites for the PC's on the WhatHifi website you'll see that they have gone to great expense to build PC's that have good sound quality.
 
http://www.evolvemedia.eu/products_lifestation.php
 
http://www.whathifi.com/reviews/home-digital-media-devices/media-centre-pcs

Check this out for better sound quality from your PC.
 
www.whathifi.com/news/jplay-aims-to-turn-any-pc-into-a-high-end-digital-transport