I’m in the process of assembling a new computer and have decided to get a aluminum case with a clear side panel. I have 2 monitors right in front of me, and the case will be (from my POV) on the right side of the monitors, almost against one and about 1 or 2 feet away from me. The clear side has the monitors next to it. I have 2 computers that will be to the left of the new tower (on the fully aluminum side), and all the computers sit on top of a few racks filled with recording equipment and effect processors.
Seeing as all the equipment is packed so tightly together, should I worry about EMF interference? I’ve read that this could be a problem with a clear side panel. I don’t have any problems at the moment, so this is only in regards to adding the case to my existing setup.
What about EMF exposure to myself? I spend a lot of time at my computer, and if this thing will be shooting some type of cosmic rays from 2 feet away, perhaps I’ll go with a more bland case.
I know this is a pretty silly question, but it’s almost time to buy the case so…
You could do a quick worst-case-scenario test by removing your case’s side panel completely and setting it up next to your monitor. My bet is that you’ll see absolutely no problems. As for EMF exposure to you, I haven’t heard of any studies that concretely linked EMF exposure to any health risks, much less the tiny amount that would be produced by an open computer.
One time I ran one of my computers with the side panel off for a few weeks and didn’t experience any problems with my gear, or any additional super powers, so that should be a good sign. I was just concerned about any possible long term problems to either my gear or myself that wouldn’t be obvious from the get go. Sounds like so far I’m in good shape.
I wouldn’t worry about personal EMI exposure, as all the reputable studies I’ve read show no real risks to health. However, you might find that your radio and TV reception suffers, and if your neighbor is close enough, he might have problems too. Your PC speakers might pick up some audible hash too.
Do they make similar cases with a fine tight mesh embedded in the clear panel and grounded to the case? I’ve never looked for one, but if they do, that would be a wonderful solution to the EMI issue.
I have an aluminum case with a side window and the only problem I really have is the fan is mounted on the window, which means I have a constant airflow across my calves. Kind of annoying. I’ve had no problems with any electronics or anything.
Thanks everyone, sounds like I’ll be fine. When you mention reception you mean over the air reception? Occasionally I’ll get those “my neighbor upstairs is vacuuming” static lines across my TV, but I wouldn’t be throwing off any waves like that, would I?
Yes, just like that. Fortunately, the EM emissions from inside a computer are quite a bit weaker than those from a vacuum cleaner (plus, the vacuum cleaner induces this hash on the power line, which is the main source for it). Unfortunately, the hash from a computer consists of square waves, which have, in theory, an infinite number of harmonics, cand can cause wide-band interrference across much of the commonly-used EM spectrum. If I run my PC with the side panel off, I can definitely see the effect on my TV, which is using rabbit ears, on the other side of the room. This EMI is most evident on channel 5 (FOX, 'round these parts), so, no great loss at least for me. Just a heads up for you in case you have your neighbor pounding on your door one day. You can greatly minimize radiated EM by installing ferrite chokes on all the wires leading into and out of the box, since the relatively long wires often make nice antennas.
What type of range would I be looking at in terms of throwing out interference? In my particular case, you either have cable or get zero reception, but I may move in a year or so, and I would like to take that into consideration now.
How does a regular plastic case minimize EMI? Is it simply because of a non transparent physical barrier, or is the inside surface coated with something?
It’s difficult to say, really. The range will be affected by things like frequency, building composition, the type and orientation of receiving antenna, or even just the mood of the EMI Fairy on that particular day. Mostly, I’d say it’s not anything to be overly concerned about.
Plastic cases provide no EMI shielding on their own. I’ve never seen an all-plastic CPU case, but I’d wager they are coated with a sprayed-on metallic coating, which is grounded through metal fingers attached to the chassis. Better monitors are shielded in this manner.
Remember, too, that EMI goes both ways. The shielding is as much to keep hash out as to keep it in. If you have an electrically noisy piece of equipment nearby, your computer may be affected by it. I had this happen with some high-voltage projects–the arcing would occassionally cause my PC to rebbot or freeze up. The EMI was getting in through the wires, in that case, I believe, since the cover was firmly installed.
The type of radio waves emitted by computers are basically radio waves. The general consensus so far is that radio waves are pretty much harmless, although if you do some research into cell phones you’ll fnd a bit of a heated battle going on. If you have a cell phone then you are getting quite a bit more exposure than you would get from a computer, and folks with cell phones aren’t dropping like flies so you can figure your computer is pretty safe.
Your monitor is a different story. Some of the radiation coming from your monitor is of a type that’s not quite so healthy. I happened to stick a geiger counter in front of a monitor once. It was a somewhat enlightening experience. It is presently thought that the exposure levels from current monitors are low enough not to be harmful (although they are certainly far enough above background level to make a geiger counter go nuts). If you have any doubts you can always switch to an LCD monitor. They don’t emit these types of radiation.
As an amateur radio operator and shortwave listener I’d like to personally wish a pox upon all perpetrators of those PC cases with big holes in the side. The amount of radio interference generated by PC’s is very significant, especially in the shortwave bands, and good shielding is essential in minimizing this. There’s already enough interference in any reasonably populated area - we don’t need to go making even more with poorly-designed PC cases. I’m pretty sure the use of many (or all) of these cases would even lead to the loss of FCC certification if the computer was tested as a whole.
Well I’ve thought about the case all day, and I think I’ll go with a fully enclosed case. In my current living situation I don’t have any problems (at least that I’m aware of), but my living situation may be changing soon, and possibly several times over the lifetime of this particular computer. Although a clear side panel would look pretty damn cool, I would rather have a machine that I have a little more confidence in. Who knows where I’ll end up, that it could screw up cell phone reception, cordless phones or TV signals of mine, or more importantly of the people I may one day live with.
I guess what I’m saying is I feel it’s more prudent to err on the side of caution, because, a clear window is not that big of a deal to me.
from 2 feet away, perhaps I’ll go with a more bland case.