Computer urban myths...for a good laugh
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Top SIX myths :haha: [/CENTER]
From Dans data
1: Microwave monitors?
Much has been made by some people - particularly those selling monitor radiation shields - of the supposed health risks of the emanations from computers in general and monitors in particular.
There is evidence that EMR (electromagnetic radiation) - specifically, the radiation from mobile phones - can have effects on living tissue beyond those expected from simple heating. But it most certainly does not follow from this that even high levels of mobile phone-type radiation actually cause any adverse effects at all in humans. Epidemiological evidence doesn't support such a conclusion, despite sensationalistic reporting of inconclusive studies. Since radiation from computers is both a great deal weaker and at very different frequencies from mobile phone radio waves, there is no reason at all to suppose that your PC is giving you cancer, or making you infertile, or whatever the panic-mongers are alleging this week.
Sitting in a bad chair typing frantically for hours isn't good for you, and if you spend all of your time in front of a PC instead of getting some exercise, your health most certainly is at risk. But since everybody already knows this and most people ignore it, it doesn't make the headlines.
2: Leaving it on
Some people leave their computers on as long as possible, on the grounds that components come under the most stress when turned off and on, and so you're less likely to have failures if you leave the power switch alone. There's only a grain of truth to this.
Rapidly cycling the power - working the power switch as if you're being paid by the click - is a bad idea for many electronic devices, including computers and monitors. If you're talking about ordinary use, however, the only problems you're likely to encounter stem from differential thermal expansion. Things get bigger as they warm up and smaller when they cool, and different components in a computer expand and contract by different amounts. The resultant mechanical stress can, theoretically at least, break traces on circuit boards and cause similar havoc.
In the real world, thermal problems with personal computers practically never have anything to do with differential expansion, but instead stem from lousy ventilation. Hot components, hard drives in particular, can barbecue themselves into an early grave. But these failures happen pretty seldom, these days, and modern hard drives are very unlikely to suffer motor or solenoid failure on startup. An old drive that's developed "stiction", where the drive has a hard time spinning up, should be left running all of the time. But that problem's never been common and is now close to unknown.
Current "green" PCs with power management features let you have most of the convenience of an always-on PC without the power bills; you can put your monitor, your hard drives, your processor and even the whole computer to sleep, and wake everything back up in a few seconds. From a differential expansion standpoint, this is the same as manually powering off the components in question. But since differential expansion is unlikely to ever do anything bad to your computer, who cares?
3: Screen savers
The screen saver is a modern art form. But what it isn't, any more, is a way of saving anybody's screen from anything.
In days of yore, monochrome monitors were quite susceptible to a phenomenon known as "burn-in" or "phosphor burn". An image shown on the monitor for a long time - a default menu, for instance - would burn in as an incurable ghostly image. Some colour monitors are still susceptible to this, but only if the image has been on the screen for a really, really long time, which is something that just doesn't happen in most applications.
All you need to protect your screen, of course, is to blank it; again, current PCs with their standby features make it easy to save electricity as well as the screen.
Some screen savers won't help with burn-in, anyway, because they have graphic elements that never move. If the screen-saver's static, it's as bad as a static application screen.
4: Don't defrag!
You don't need to defragment your hard drive very often. Modern drive optimisers like Windows 98's Defrag which position program data according to how often you use it can, indeed, improve performance a bit, but there's no reason for even a heavily used computer to be defragmented every week, or even every month. Yes, it'll be faster if you do. But the difference will probably be tiny.
Hard drive performance in toto makes very little difference to system performance, on machines with adequate physical RAM. The difference in performance between unfragmented and moderately fragmented drives is small, and the larger the drive, for a given level of filesystem activity, the less fragmentation it will suffer.
If you're using Windows NT or 2000 and NTFS-formatted drives, bear in mind that NTFS is famously insensitive to fragmentation - which is just as well, because it's hard to do anything with NTFS without it fragmenting data. This is why Microsoft claimed for so long that NTFS was immune to fragmentation, and no defrag utility was needed at all!
NTFS performs poorly on old drives with lousy seek speed, but the trade-off is that its performance as fragmentation increases remains quite steady. Once the NTFS Master File Table (MFT) becomes fragmented, you can indeed lose performance, but how much you lose still depends on what files are where and how you use the computer. Look at overall system performance, rather than just disk subsystem performance, and the difference due to fragmentation often fades into the noise.
How much effect fragmentation has on performance depends heavily on what files are fragmented, where the fragments lie, and what filesystem you're using. Generally speaking, the upshot of all this is that frequent ritualistic defragmentation, in the absence of a significant measured performance loss (not just how your computer "feels" to you), is, obviously, unnecessary.
Fragmentation certainly can severely degrade system performance, especially on Windows machines without enough physical RAM, or which are doing very disk-intensive tasks like serious database work or high data rate video editing. Defrag weekly, though, and you're probably just going to grow hair on the palms of your hands.
5: Monster swap files
Twiddling Windows' virtual memory settings (setting a static swap file size, for instance) doesn't improve Windows 98 or ME's performance much, if at all, although it can help Windows 95. If you choose to do it, don't use the goofy rule-of-thumb that your virtual memory should be some set multiple of your physical memory. You need as much memory as all of the programs you want to run at once will consume, and no more. The more physical memory a given system has, the less swap file size it needs, all other things being equal.
This goes for Windows NT and 2000, too; they let you specify swap file sizes on multiple different drives, which is nice to split swap activity over different physical devices for performance purposes. But going bananas on a multi-drive machine and giving yourself a permanent 3500 megabyte memory pool is pointless. Set your minimum total swap to roughly match your average memory pool needs, if you like (Ctrl-Alt-Del, Task Manager, Performance tab; the "Peak" number shows the most memory your system's used this session), but no tweaking beyond that is needed.
6: Magnetic mayhem
One of the basic tips in every computers-for-*****s book is to keep your floppy disks and other magnetic media away from magnetic fields, lest your data be wiped.
Magnetic fields can, indeed, eat data, but the usual suspects aren't generally the problem.
Every ordinary cone-type speaker driver has a large permanent magnet on its back, to give its electromagnetic voice coil something to push against. "Shielded" speakers neutralise the magnetic field with another, opposed magnet glued to the voice coil one, which reduces the driver's efficiency but does the job. An unshielded speaker's magnetic field is clearly apparent if you put it too close to your monitor - the image will distort and change colour, and in extreme cases stay that way, despite the monitor's built in "degaussing" circuit, until someone makes magic passes over the device with a degaussing wand.
But putting a floppy disk on top of an unshielded speaker probably won't hurt the data on the disk at all. This is because it's the change in magnetic field strength, more than the actual peak strength, that erases disks. For this reason, a rapidly oscillating magnetic field is much more dangerous than the static one from a simple permanent magnet.
A old fashioned bell-ringer telephone contains a pulsing electromagnet that moves its bell-clapper, and a disk leant up against it is likely to be a goner in short order. The abovementioned monitor degauss circuit will zap disks left atop the screen pretty well, too, and some printers, especially older dot matrix models, contain quite large and poorly magnetically shielded motors.
Essentially, any electronic device with moving parts may be able to zot your floppies, tapes and Zip disks. It doesn't have to be able to pick up a paper clip to be dangerous.
