Make an I/O Shield???

[Maccer101]

The Dell is a STD mATX G33 mobo

[Pob255]

Is it really necessary? What about cases with an acrylic window in a side panel - surely they're not capable of blocking EM waves?

He's hit the nail on the head here.
Acrylic windows do not block any RFI* (please stop saying EM the electro magnetic spectrum covers a lot of stuff, including light)
Now yes it is possible for a pc to interfere with TV and radio signals however the range is short. The main culprits are wire coils, the biggest and most powerful of which are in your psu.
Many household appliances have a far greater capacity to cause RFI than your average pc, esp. as the noisiest part is the most shielded
Don't know if our next door has any pc's but every time they use there vacume cleaner certain tv channels get bad interference.

* Radio Frequency Interference i.e. signals that could possibly interfere with TV’s and radios

[kalniel]

Acrylic windows do not block any RFI* (please stop saying EM the electro magnetic spectrum covers a lot of stuff, including light)

But it's still the right term - just because RFI is a subset of EMI doesn't mean that EMI isn't appropriate

[watercooled]

I did mean RF waves - I was tired when I made that post, but EM is still mostly true of acrylic which blocks hardly any EM waves, including visible light if it's transparent.

[idlehanz]

LOOK OUT it's the EMI Police!!!!

Don't worry about this, they are overstreched and have much bigger fish to fry!!

It's highly unlikely that what you do will cause any interferance. You'd probably notice it first long before anyone else did even then they'd have to sniff you out!! Unlike the kiddy round my way with moped that chucks out some serious electrical noise that locks up my digital TV signal every time he goes past. I should report him, but that would be even more effort than moving for the remote!!

[watercooled]

Some cases like the Antec Skeleton are completely open, along with other workbench cases. And why do so many motherboards come with spread spectrum?

[kalniel]

Some cases like the Antec Skeleton are completely open, along with other workbench cases.

Not in the EU likely - hence why windowed cases are meant to come with a grill for EU use.

And why do so many motherboards come with spread spectrum?

Well that gives you an example of the problem - it's bad enough that they have to give the option to spread the interference out over a wider bandwidth to try and reduce it's strength.

[Pob255]

Ahh spectrum spread is different and could be a more important issue for having an IO shield
Basically we're talking about the reverse, so other object produceing large amounts of RFI and it actually getting picked up be the wires of the computer and induces a voltage, spectrum spread is supposed to level out any sudden peaks or opposing currents.
How much this will effect you? depends on the environment the pc is in, if it's sitting next to a large powerful fm transmitter then you could potentially get rfi problems.

One thing I will note here is cables, cables comming out of the back of your pc can often be the biggest aerial for receiving signals.
I used to use a cheap stereo system for pc speakers, connected by a 3m length of cheap cable, worked fine until a bus went past when I'd get two loud bleeps from the stereo.
It didn't do any damage or cause instability was just annoying.

[watercooled]

That's what the ferrite rings surrounding some external wires are for - you can buy them separately to reduce interference:


The Antec Skeleton is available in the UK: http://www.scan.co.uk/Products/Antec...air-enclosures)

I've also had 2 PCs running while open and a TV about 2 meters away didn't show any noticeable RFI - and that was an analogue channel.

[idlehanz]

Some cases like the Antec Skeleton are completely open, along with other workbench cases. And why do so many motherboards come with spread spectrum?

Spread Specturm, lol: The brief answer is that it's a little kinder when EMC testing so make gaining approval easier. So you'll always tend to see this option in the BIOS.

Well you can assume that Antec Skeleton in its own right is no doubt CE compliant.

Each manufacturer assumes resonsibility for their component to be CE compliant. But when you add these together, especially in terms of EMI at least, you do not necessay get a CE compliant system.

This is why CE+CE does not equal CE.

You can be in no doubt, that once the Antec Skeleton has all components assembled it would piss emmisions every where and fail in any test chamber.

But for the hobbiest, you can put these components together and use them yourself.
It's only if your doing it for commercial gain that it becomes a bit of an issue, bit like Tradesman v DIY in liability terms.

At this point what we need is an excitable EMC/EMI expert (Anechoic chamber monkey) to give the full low down on this.