Slashdot Mirror

← Back to Stories (view on slashdot.org)

The Computer as Microwave?

Posted by Cliff on from the the-consequences-of-the-Ghz-race dept.

Clan Hanna asks: "With the newest processors that AMD and Intel have released, running at 1.0 gigahertz, chip designers may soon have a new problem on their hands more than can simply be solved by placing a bigger heatsync on the motherboard. Microwave frequencies run from 1 gigahertz to 1 terahertz. Currently processors heat up because they emit infrared radiation, but what is going to happen when they start to emit -microwave- radiation? I'm sure chip designers think about this in the back of their minds, but I'm just wondering if they have considered any real world solutions. If so, I'd love to find out about them."

7 of 32 comments (clear)

  1. Flatscreens by jerrol · · Score: 3

    They emit very little radiation...

    There is basically a VERY bright lamp that is shown through a number of colored LCD screens. The Plasma displays work similarly. Electroluminescent displays emit even less...

    Any of these is much better than the electron gun in the back of CRTs. (basically a small particle accelerator..)

    Of course, if you are truly worried about radiation poisoning: never fly (cosmic rays), don't get X-rays (X-rays), stay away from cinderblocks (alpha-emitter), ditch that glow-in-the-dark watch (radioactive), discard you're smoke detector (radioactive), stay away from the Northeast (radon, radioactive)...oh hell, just leave the planet beacause a couple of years ago, a satellite with a nuclear reactor onboard burnt up on re-entry and spread plutonium over the entire planet, of course, interplanetary travel opens up another can of worms...

    =)

    --
    Never let your fears overcome your dreams.
  2. Microwaves aren't that bad by mind21_98 · · Score: 3

    I'm an amateur radio operator, and the thing we have to watch out for is RF radiation. At the microwave bands, the body starts absorbing more radiation and the internal tissue starts heating up *shudder*. If you're exposed for long periods of time to this, eventually you get stuff like cataracts, cancer and so forth.

    However, to my understanding all modern computers are supposed to comply with FCC Part B regulations. This means that they don't emit anything that could cause interference or other harm. In other words, you have nothing to worry about unless you run the system with the case open.

    --
    US businesses that currently accept chip and PIN/signature
    1. Re:Microwaves aren't that bad by RGRistroph · · Score: 3

      Yeah, but a lot of people run their computers with the case open, or without a case at all (you can just screw everthing into a plastic milk crate, or worse; just look at some of the overclocked systems -- a pile of wires and boards on the kitchen table or in the freezer or in cooled mineral oil).

      Before I buy a chip running at that frequency, I'd like to see some specs on exactly what I can and cannot do with it. If I need to keep it in a case that meets certain specifications, I should know that; is it safe to just not screw in the panels on the case, or should I always have everything tightened up before powering on ? I would prefer to have the processor package do all the necessary shielding for me.

      What about those guys doing wearable computing ? I know Steve Mann and that Media Lab freak club were walking around MIT with computers butt packs for a while. For what processors they had there was probably no danger, but with a gigahertz plus processor hanging over the genital area or close to your body at all -- cancer at least only affects the person who decided ot wear the thing, a birth defect punishes a child for the parent's negligence.

      I would prefer to get the information from an independent source; if AMD or Intel said that it was dangerous if not run as shipped, the information would be suspect because they might just be trying to scare off the overclockers, and if they said it would always be safe, they might just be hiding the truth for marketing reasons.

      So I would like to see some overclockers and someone with access to the right kind of equipment test the newest processors at some really high clock rates (even if the processor was unstable at that rate) and publish the results. The "right kind of equipment" is the kicker here -- I've heard those electrical isolation chambers they use to test the meeting of FCC specs are very expensive.

      I am planning to buy a really fast alpha in a few months after I move to my new place. I've heard rumours of 1.4 and 1.6 GH by then. I'll just get some really long keyboard and monitor cables until I see some trustable information on this issue. Whatever the manufacturer says, I'll still trust 1/R^2 -- you can't beat basic physics.

      Incidentally -- does anyone know if these expensive flat screen monitors produce signifcantly less EM radiation than the good old cathode ray tube ? I think the fact that they use less power is a good sign.

  3. It's even more mundane than that. by Tau+Zero · · Score: 3
    ...call me an EE major (I am one :-) but I belive infrared is ABOVE microwave in frequency.
    Call me a double-E (I have a degree that says that I am). Infrared is indeed "above" (greater energy, shorter wavelength) microwave radiation. The clock signal does affect the radiation from a device; the faster the clock and the sharper the edges, the more RF radiation you get from the leads and such. This isn't going to cook you, but RFI and Tempest emissions ought to be kept in mind.

    Cliff wrote:

    Currently processors heat up because they emit infrared radiation, but what is going to happen when they start to emit -microwave- radiation?
    Well, Cliff ol' boy, I've got news for you: processors don't heat up because they emit infrared radiation, they emit infrared radiation period. So do you. A square meter of blackbody radiator at skin temperature emits about 450 watts[1], mostly in the infrared. However, some of it is actually at longer wavelengths, down into the microwaves. (YOU are a MICROWAVE EMITTER! And if you don't pay me $10,000, I'll TELL YOUR FRIENDS AND FAMILY!)

    This property is used all the time. One of the methods for sensing temperature remotely is with microwave radiometry; it's how the surface temperature of Venus was determined before probes were ever sent there, and the bulk temperature of Earth's atmosphere is measured by satellite sensors using that same technique to this very day.

    You don't have to worry about microwave emissions from a CPU chip, even if it's running at a couple of GHz. The chip carrier itself usually has a metal plate for heat dissipation, forming a ground plane; ground planes provide "equal and opposite" mirror currents and mostly cancel the emissions. The metal lid is another ground plane. Even at 3 GHz, a wavelength is 10 centimeters; most traces on the chip are but a fraction of a millimeter long, and don't have the physical size to radiate well. What radiation they do emit will be cancelled by image currents in the ground planes and confined inside the chip carrier until it is absorbed by resistance in the silicon itself. The biggest issue is emissions from leads which go out of the chip itself, and those are usually running at a much lower frequency than the CPU core. What gets out is microwatts at most; this can be troublesome, but danger to people is way down on the list of concerns.

    I think the summary is, no need to worry yet but you should probably do some reading so that you will know if and when you should worry in the future.

    [1] Blackbody radiation flux is determined by the absolute temperature and Boltzmann's constant; the formula for the radiation per unit area is flux = 5.67*10^(-8) W/m^2/K^4 * temperature^4, so the heat flux increases as the fourth power of temperature.
    --

    --
    Time is Nature's way of keeping everything from happening at once... the bitch.
  4. apples and oranges by Bourbon+Man · · Score: 3

    Here is why you need not worry. We are talking about two completely different types of equipment. A microwave oven has a special device in it called a magnetron that produces microwave radiation. It is usually powered by a step-up transformer that puts out around 3000 volts. It was expressly designed to transmit radiation in the form of microwaves (a radio waveform). A CPU has no emitter, i.e it has no parts in it designed to emit radiation. It was designed to push electrons through predetermined paths. There is a big diference between something operating at 1Ghz, and something emitting a waveform at 1Ghz. The infrared (also known as heat) produced by a CPU is not directly a product of it's speed, it is a byproduct of resistance (basically the friction of electrons moving through an imperfect conductor). Chip manufacturers are reducing heat and increasing speed *at the same time* by switching to copper-based chips because copper is a superior conductor. They are also lowering the voltage needed by the chips to the sub-2 volt range, a long ways from the 3000 volts a microwave uses.

  5. Wait a minute... by dufke · · Score: 5

    ...call me an EE major (I am one :-) but I belive infrared is ABOVE microwave in frequency. Anyway, most of the heat produced by a CPU is transfered through heat conduction, not radiation. I don't think the actual clock signal would cause much radiation. Clocking a CPU higher may increase heat production, but the frequency of the radiation (if any) is not directly related to the clock frequency.

    Anyway, even if it did, the high-amplitude microwaves in an oven are stopped by rather thin sheets of steel. And the amplitude from the CPU must be lower. Remember, your oven draws multiple kW, while I damn hope your CPU keeps below 100W. (Otherwise, you have an Alpha, and I WANT IT! :-)
    -

    --
    __
    Comment submitted. There will be a delay before you understand what you posted.
  6. I get a little upset... by jdwilso2 · · Score: 4

    When /. posts a bogus story like this one... uPs aren't gonna produce any harmful "radiation" such as this story suggests. Sure, every electrical device emmits a multitude of interferance, but to claim that when processors start getting above 1GHz I can cook my TV dinner in my case is rediculous. Power has a great deal to do with such things, and so does the appication. I mean, come on... Let's be serious, a 2.4GHz coordless phone meets FCC specs, and it's *transmitting* it's 2.4GHz signal... RF stuff can't hurt you, and it's moving through all the space around you. Hell, the military use spread spectrum encoded wireless transmissions whose carrier frequencies are 10GHz and UP! And if RF doesn't hurt you, ain't no clocked digital logic circuit gonna byte you. Especially at those exceedingly low frequencies of under 100GHz. It's all about power guys... Do some reaserch before you start spewing your crap all over me. It's all about the power...