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I am currently computer shopping and was given what seemed strange advice by a friend yesterday. She had been told to avoid 60 and 66 MHz speed computers because they get very hot and make rooms where they are being used uncomfortable. The advice came from my friend's "computer guru" who I suspect only deals with PCs, not Macs. I'm shopping for a Power Mac. Does anyone out there know whether this "hot" rumor has any basis in reality? If so, is it true for Macs as well as PCs?
41 responses total.
The hot rumor has some basis in reality -- on Pentiums. I'm not sure how noticable a difference they made as far as room temperature went, but they apparrently got hot enough for the heat to be bad for the chip, leading to such jokes as, "Pentium: melts in your motherboard, not in your hand." If you're buying a PowerPC, don't be deterred by Pentium problems. They're different chips. Also unlike the Pentium, the PowerPC knows how to divide.
Heat a room with your Pentium? I don't think so. I suspect the heat your friend was feeling was from tempers building trying to get it to work properly In all honesty, if the pentium chip disipates more than 10 watts of power, you could melt solder with it. A bit more heat than a night light would give off. Taking it to an unrealistic extreme, your average Pentium PC is going to come with a 250 or so watt power supply. It can't supply any more than that. (I'll bet most clone supplies would die if they had to supply that level of power for any length of time.) The same amount of power given off by five 50 watt light bulbs. Can one heat the room in question with five 50 W bulbs?
And if the heat was causing problems for the chips, wouldn't that indicate that it wasn't disipating the heat very well, and was holding it in instead?
There's a very nice video of an intel worker frying an *egg* on a pentium. Power dissipation and temperature aren't necessarily related - even a tiny incandescent light bulb internally manages very fiery temperatures, while dissipatingly only a tiny fraction of the power of a large wall plug radiant electric heater. 5 50 W lightbulbs is actually equivalent to a 850 btu/hr heater - or about 1/6th of an ordinary room electric heater. It's certainly capable noticeably raising the temperature of a small room. Don't forget, too, to add in extra heat from the monitor (even an old tiny b/w monitor is good for 60 w - and some of these big modern color displays are a lot more thirsty). Modems can also be somewhat power hungry, especially older higher speed units - and the wall plug transformers for some can also get kind of warm. The thing about all computer equipement is, whatever else it's good for, it's *always* at least 99% efficient at converting all of the electricity fed into it, into heat. People, too, are another source of heat - for people just standing around, the usual figure is something like 60 w. That's why crowded parties with 20-30 folks in a room can get kind of warm.
Most high speed PC-type computers have fans on the chip to make sure
the chip doesn't get too hot. I don't know if that's true for Macintoshes
as well, but I expect it is. I don't know of anyone who has a problem
with his high-speed PC generating too much heat for his room, not because
of the chip speed, anyway. People with clunky old MF/M or ESDI hard
drives, and people with large screen monitors (17" and bigger), and people
with computers loaded down with lots of components, are more likely to
have heat problems in their rooms.
I knew someone with 8 small hard drives on his CP/M computer in
college; not only did the computer generate enough heat to warm up his
dorm room in short order, but when he started the thing up, it sounded
like an airplane taking off.
Arbornet ran a computer like Grex for a night in the tiny office in
the NEW Center; after 8 hours, the room felt like it was about 120 degrees
inside (I was told). Arbornet runs 2 486/33 computers in that office
(and 24 modems) without any noticeable problems due to heat.
I don't think you'll have any problem with your Power Mac, but if
you're worried about it, touch the case on one that runs most of the time
where you plan to buy your computer. If the case is noticeably warm,
it'll give you some indication as to how much heat the computer will
generate in your house. For comparison, try touching a light bulb that's
been on for an hour or so. (-:
I have an IBM CGA monitor from 1983 that makes a very nice space heater. I'm very glad I'm not using it on my computer anymore, for more reasons than just the graphics.
I've never heard of tiny fans on MPU's until the pentium came out. I haven't actually cracked the case of a Power Mac yet, but to the best of my knowledge, there aren't any of those ridiculous of those ridiculous tiny fans inside. I know there aren't any of them in a Quadra (68040) or inside an RS/6K (Power2 chipset, the big brother to the power PC chip.)
Thanks for all of the input, everyone. I suspected as much... but it was worth asking before I shell out thousands of $$!
I recall that the PowerPC Motorola RISC chip draws a lot less power than the Pentium, while doing the same "work". Does anyone have the figures on that? Of course, everything else - monitor, drives, loudspeakers (;->) - consume about the same power. Oh, for the record: the PowerBook does not have a fan - except us PowerBook fans.
Marcus, Jemmie Wang of CCS first started talking about CPU fans when he
was pushing his DX2/50 to 66 MHz. When Everex was trying to push an early
486 chip to 80 MHz, they used a water tower to cool it. That was at least
a couple of years ago... Everex went bankrupt about then.
Fans, anyway, are common on high-speed 486 chips and on Pentiums. If
they aren't being used on Motorola chips yet, I think they surely will be
soon as Motorola pushes their chips to keep up with Intel chips.
I think I remember noticing a heat sink on my step mom's PowerPC, but I'm not sure about that.
Actually, John - I would be surprised if Motorola did so. Fans are an extra cost option and something else to break, and chips that take that much power aren't as useful for many applications. One of the markets Motorola has been in for a long time is that of automotive electronics - and in fact one auto company has already comitted to using some flavour of power PC chip in transmissions. Indeed, fans of any type are bad enough for automotive applications that they've been fooling around with all sorts of passive chip coolers long before they found their way into personal computers. A chip that requires a CPU fan just isn't going to make it. For portable applications, too, low power is a "must". Quite aside from the problems of packaging a CPU fan into a portable - something that eats that much power will do nothing good for battery lifetime or weight - 2 key parameters in portable design. These are important markets for Motorola; they are unlikely to favor designs that would close them out of these markets. The pentium needs fans because, in a sense, it's pushing the technology beyond what it's capable of. The PowerPC is a simplier yet more powerful chip - so it doesn't need to ride the leading edge of integration quite so hard.
Heat is what kills most electronics, contraction and expansion being the biggest culprit. Fans can do a lot to help inprove heat disipation. Fans, however, are mechanical devices and will not have the MTBF of a reasonably designed chip. I've seen too many clone power supply fans fail to have much faith in them keeping a Pentium CPU from washing away in its own puddle of solder. In the Jan. 12, 1995 issue of MACHINE DESIGN, they show the concept of using heat piles to carry the heat away from the CPU. Oddy enough, the drawing shows a Pentium chip in a laptop with the heat pipe on top of it. The artist didn't elaborate on the power source for this confowlation. Perhaps a deep-discharge truck battery? ;)
I've also seen heat sinks on some processors. Maybe these are more
common than fans.
If your 80 MHz processor burns out after a year because the fan died,
and you have to replace it, what are you going to replace it with --
another 80 MHz processor, or the newest, latest processor that will fit in
the same slot? I think a lot of people are opting for whatever's being
touted as "the latest". This must break Intel's heart.
At one point, I saw a power chart for at least 6 risc & cisc
chips, but now I can't find it. I did, however,
find this comparison of the PowerPC and Alpha:
PowerPC 601 Alpha 21064
Technology 0.6-micron CMOS 0.75-micron CMOS
Levels of metal 4 3
Die size 1.09 cm sq 2.33 cm sq
# Transistors 2.8 million 1.68 million
Total cache (I+D) 32 Kbyte 16 Kbyte
Package 304-pin QFP 431-pin PGA
Clock frequency 50 Mhz, init. 150 to 200 Mhz.
Power dissipation 9 watts @ 50 Mhz 30 watts @ 200 Mhz.
This is ca. Jan 1994, so faster 601's may be out today. Particularly
for CMOS, power dissipation is largely proportional to speed - so a 25
Mhz 601 would likely only consume 5 watts. Within a particular batch,
individual chips will often run faster, so it's quite possible that by
retesting 601's at a higher speed and then running them with CPU fans,
one could have a 75 Mhz 601. At one point, a company was doing
something like this with 68040's and Macintoshes.
To answer the original poster's question: Yes, avoid the 60 and 66 mhz pentiums. They get too hot. No, they don't have enough heat to significantly affect the temperature of the room, but the heat is bad for the chip itself. I have heard reports that the extreme heat inside a 66 mhz pentium is enough to cause slow metal migration on the circuit pathways that could lead to premature failure of most 60/66 pentiums after only a few years. This only applys to 66mhz pentiums. 66mhz 486 DX2's are fine.
(The original poster was asking about PowerPCs, which are also fine)
Yep, 7100 has a massive heat sink. No fan.
If you do get a system with an on-chip fan, be *careful*. I know of one case where a cable got in the way of the fan, preventing it from turning. The system produced some really strange symptoms before the cause was discovered, I think.
Also, many of those fans will die after 2 or 3 years of use. Most of them use bushings impregnated with low-grade oil and simply dry/gunk up. Ball bearing fans are much better. Same goes for the fans they put in most of the clone power supplies.
Fans also cause a lot of dust built up in PCs, which can cause all sorts of other problems if it isn't kept in check. BTW, this is my first time reading this conference, and I it was great. Nowadays you wouldn't dream of buying a machine without a fan, and most will have a heat sink. I just picked up a new machine and the sink is bigger than the chip by several times :P Interesting how attitudes change...
An air compressor fitted with a hose and air gun does a decent job of blowing the dust out of computers and power supplies. I have also noticed a trend towards lower speeds and ball bearings in fans.
COMPAQ is one of the few companies that still doesn't use chip fans. Their preference is for very large heatsinks, sometimes combined with extra case fans.
the fewer mechanical parts, the better the reliability. A heatsink will outlast any fan.
Amen. CPU fans were an awful kludge. I haven't yet seen chip fans on anything but PC's. "Serious" computers, ie, sparc, rs/6k, etc., use heat sinks.
Harummph. "Serious" computers need a chilled water supply. ;)
"Seriously silly", you mean. My office has more computing power in it than the most powerful water cooled mainframe the University has ever owned (an IBM ES/9000 model 720 6 processor complex). Oh yes, they put some seriously poisonous stuff into that water too. It's nothing you would want to pour down the drain unless you didn't care about the environment. Water does have its problems too, like being corrosive and conductive. The *real* ultimate in cooling is liquid freon. This was used in the big cray's. Crays were, of course, unique in having built-in beer coolers. The mean time to repair on the cray is, by a curious coincidence, almost *exactly* the time it takes to cool a beer down for human consumption.
I like my beer uncooled, so I'm "faster than a Cray".
cray just did a presenation to aacs last month - amazing! and cooling was a large part of their advancements. now, the cpu 'shell' is pointed down and liquid is sprayed UP to vaporize (latent heat stuff) and cool. what's amazing is that the liquid used comes from the medical profession. i dont remember it's name/nomenclature but it is a *blood substitute*, directly injectable! (in medical application).
Is this that stuff that can hold massive amounts of oxygen? I remember seeing a demo where a mouse was submerged in it. The liquid held so much oxygen the mouse could survive by breathing it, and didn't drown.
There's a web page here that talks about it:
http://www.scienceweb.org/movies/abyss.html
and yes, it's oxygenated fluorocarbons. I don't think it's actually
technically correct to say that the subject "breaths" - lungs are
designed to pump air not fluid, and there's instead a mechanical pump
involved to move the fluid. (If you were designing an organ as a fluid
based oxygen/CO2 exchanger, you'd probably wind up with something like
fish gills -- fluid passing over a network of blood containing veins
rather than veins surround a network of dead-end sacks.)
Fluorocarbons have long been used in refrigeration. Classical freon is
a fluorocarbons -- actually CCl2F2. Current replacements are also
fluorocarbons but don't contain chlorine which is supposed to make them
environmentally more friendly. You don't want to run any fluorocarbons
(except *maybe* teflon) through an open flame however - nasty nasty
combustion products. That's basically why Halon is no longer favoured
as a fire suppressant - though I'm not sure which halogens it actually
contains.
Halon is no longer favored because it's now illegal to manufacture. It's an ozone-depleting chemical. Halon already in existance is allowed to be recycled into new fire extinguishers, though, mostly because discharging a fire extinguisher into a fire consumes most of the halon. (The official method for disposing of it is to inject it into an incinerator.) Halon extinguishers are pretty good choices for vehicles, because for a given size they're much more effective than a CO2 extinguisher. They chemically interrupt the combustion process instead of just smothering the fire, apparently.
How can carbon be any better than halon? Co2 is what's causing most of the global warming but you don't need me to state that obvious fact that 3rd graders know. :P I just don't see the logic unless Halon is really bad, and co2 is a lesser evil (Yeah I know we breathe it out and plants need it I just like saying "lesser evil"). I don't even know why I'm writing this because I have no clue what I'm takling about. ^_^
Halon was one of the chemicals implicated in the 'ozone hole', so it's hard to say if it's 'worse', it's just 'different'. Currently no chemicals are outlawed because of global warming potential, and I'd guess the amount of CO2 discharged from fire extinguishers is pretty small compared to other sources.
Yeah, compared to cars or factories or any gasoline or dieseline motors...
Halon probably has chlorine in it - that makes it an ozone depleting substance just like CCl2F2 and lots worse than just ordinary fossil carbon. Note that CO2 from "biological" sources is different than CO2 from fossil fuel; while both behave the same, the problem is not that we have CO2 in the atmosphere but that we have lots more than we used to, and nobody quite knows what magnitude of climate change we can expect from this. If we could, starting tomorrow, limit ourselves entirely to only releasing CO2 derived from biological sources, and not burn any more fossil carbon, that would put an important cap on global warming. It's not clear that we can sustain our current standard of living doing so, nor is it clear what shape the world will be in when we collectively figure out we have to stop releasing fossil carbon into the biosphere.
Halon 1301 bromotrifluoromethane. Another Halon is 1211 (chlorobromodifluoromethane). The different compositions give the substances different properties for different applications. All the Halons contain bromine, which acts as a free-radical quencher, which tends to quench flame reactions.
Halon 1301 sounds like it "ought" to not contribute to ozone layer thinning. Once upon a time, at various computer trade shows, you'd see the obligatory halon demonstration. This consisted of plexiglass booth, about the size of a telephone booth, which the demonstrator sales person would use to show off the advantages of halon. Picture an older guy, typical used car dealer type in appearance, grey hair, suit and all - a marked contrast to the swarms of computer people found at most of these things. Typically he'd light up his cigar, bring his lighter in with him, or he'd have a swatch of cloth doused with some flammable liquid and flamming merrily away threatening to singe his ears, then there would be a more or less drammatic "swoosh", clouds of grey "stuff" would rise up from the base of the booth and fill it, obscuring the demonstrator, but if you looked carefully you could see the flames vanish even faster, then the demonstrator would step out, apparently unharmed, to repeat this with variations at periodic intervals to an appreciative crowd. High circus, all in all. Supposedly, even today, the two halons aren't supposed to be at all carcinogenic, although they do pose a known risk as an asphyxiant. I've never seen any good reference, but I've heard a rumour that it turned out the demonstrators had various bad health problems after a while. I suppose it could be simply the smoking, although it strikes me that breathing the combustion products of halon putting a fire out in a confined space might not be a very good idea.
There's a lot of information about Halon extinguishers here: http://www.h3r.com/index.htm
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- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss