[Ca$h68]

Heheh. Well.. today I ripped up both my iMacs, and I also flipped the fans around in both of them. Why? I read that flipping the fans would cool down the CPU, as currently they are set up by blowing downward, thus pushing hot monitor air onto the CPU. So, in theory, flipping them would be a better move, as it would be sucking cold air through the bottom of the iMac onto the chip. Right? WRONG. Well,.... the chip might actually be cooler, but HOLY SHIZNIT did stuff get hot. it might be due to the fact of the cheap Quantam Fireball 12 gig, or just the CD rom, but I was installing mac 8.6, and the CD ROM was BEYOND hot... it was almost MELTING the CD. Ok, little exaggeration there, but it heated up the CD to the point where it was uncomfortable on my leg. IT WAS FREAKING HOT! So yeah, word of advice...do not flip your fan unless you want melted CDs and scalding CD ROMS.

Peace

Ca$h

[slboett]

I guess that's why Apple spends MILLIONS on R&D, Ca$h ol' boy...

Scott

[Ca$h68]

Ha. Ok whatever. Yeah, they spend MILLIONS so they can include :

A. The crappiest, most useless pathetic, already out of date video card on the planet

B. Cool software when you get your computer like Williamson's COOKING or some other stupid CDs.

C. They spent MILLIONS on designing a computer to blow hot moniter air on the CPU. Boy why didnt I think of that?! Oh yeah, cuz its a STUPID idea.

Apple pulls some real boners quite often, and I read somewhere that flipping it improves performance. It might, but everything else sure heats up.

Ca$h

you could flip your fan, get a cheap case, and run an extra long IDE cable out the side to the cd-rom in the cheap case of course, you'd have a huge gaping hole in the front...

[thirtyfootsmurf]

Umm...for the original poster here, the "hot moniter air" as you say, would not fall on the fan, it rises throught the vents on top.

In actuality, you are sucking the hot air from the chip (which does not do much) whereas it is better to cool something w/ air or water (whatever the thing might be) BLOWING on it. You have more air vloume going on the chip rather than from the chip.
I do not mean to be scarcastic, just informative.



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What's that stuff in my toilet? Where are my pants? Why can't those damn monkeys stop banging those sledgehammers on my head?

[slboett]

Damn it Ca$h, please go to work for Apple so we don't have to put up with all this crap!
As for the comment that blowing air on the processor will cool it better or more, more does not necessarily mean better. I'm sure that what cooling does take place falls within the specs of the chip(s). Things electronic (and mechanical) can require a certain amount of heat to function at optimal levels. Does anyone here know what the heat/performace specs are for Motorola processors? That would be necessary before second-guessing real engineers...

Scott

[Ca$h68]

Sucking, blowing, it matters not to me. Nor a chip. As long as air is moving PAST and AROUND and THROUGH the heatsink it will work. Ever heard of someone installing their heatsink the wrong direction, so it burned up their chip? Nope. It doesnt matter if I had put the fan BLOWING the hot monitor air (more later) on the chip, or SUCKING cold air from the bottom of the machine accross it. As long as air moves through the heatsink, the chip will get cool.

Secondly, ... ok, you state that the fan is not blowing hot monitor air on the chip, because the hot monitor air rises through the top... ok... this isnt exactly rocket science here... if air is moving out the top, where is the air coming in? It has to be replaced, right? Yep. And that FAN isnt pushing air up, its also sucking air downward, onto the chip. So basically you have a box. On the top is vents for hot monitor air. On the bottom is a fan blowing downward. See how this isnt the most efficient idea? A better one would be so the air moves THROUGH the box, aka, having the fan and the hot air moving the same direction. Hence the theory that it would work much better. But, the hard drive sucks (Quantum Fireball) and heats up the CD ROM hardcore, so I cant do it. Maybe if I added more fans blowing accross the harddrive... we'll see in the future. Hehe.

Ca$h

If you compare the heat put out by the processor and by the monitor, you will find that the monitor puts out vastly more heat. The G3 is a very low-power processor; the one in the iMac probably takes maybe five watts. The monitor, on the other hand, probably takes something like forty watts. The monitor needs the cooling badly, but the processor doesn't.

Is this a good design? There's only one metric that ultimately counts. Does the machine work, and perform as specified? You bet. Does the machine work, and perform as specified when you flip the fan so it blows air directly on the processor? Nope. Which one is better? You decide.

[Ca$h68]

Mine worked both ways. But the CD ROM heated up in one of them... partially due to my Quantum Fireball HD... I've noticed my drive is always kinda warm, but it gets hot if I am doing a lot of stuff.

Ca$h

[bugs]

> The G3 is a very low-power processor;
> the one in the iMac probably takes maybe
> five watts. The monitor, on the other hand,
> probably takes something like forty watts.

Yes, but the processor concentrates that heat into a flat square inch while the monitor distributes it over a relatively huge area. Additionally, much of the monitor's heat is in the heater element inside the tube where it is essential for proper functioning.

In the end, it is still the processor that benefits most from cooling- especially if you want to mess with your speed like many seem to in this forum.

[ThinkInsane]

"Sucking, blowing, it matters not to me"? I thought those were the two biggest things in your life.... I give you credit though cash, you can work in a comment about your sh*tty vid card in any post

[keyser_soze]

but u cash u forget the aerodynamic shape of the iMac. The fan pushing air down will curve around the bottom and go back up and out the top, getting the max amount of fresh cool air throughout the inside.

It's like a house with no a/c. If u have to use the windows to cool a house, you can

• open the top of the window
• open the bottom of the window, or
• crack the top and the bottom a few inches

even though the windows are barely cracked compared to being fully open, u get a better airflow (hot air goes out top, cold comes in the bottom)
like the man said, apple spends millions on R&D, they probably figured out the best place and position for the fan
hehe, that tact remark on the other thread had me rolling on the floor for a good 5 minutes

[This message has been edited by keyser_soze (edited 05-25-2000).]

[Feathers]

Yeah Ca$h,

What were you thinking? I thought that the flipping the fan BS had been nixed months ago. For a otherwise reasonably bright boy you do seem to have brief moments of galactic stupidity!

Of course, it could be worse, your moments could last years, like they seem to with Dragonlance!!!!

[Ca$h68]

Dragonlance was a wishy-washy idiot. Oh boy macs rule! oh wait, they suck! moron. I like macs. I hate my video card. Nothing I've said has ever changed. Besides, flipping the fan makes sense on paper, doesnt it? I dont call it galactic stupidity, I call it effort. And a lesson. it does NOT work, despite what that iMac overclocking guy says.

Ca$h

why dont you just put an air conditioning unit in your imac.
the pc tech.

What really important is the

1) contact of heatsink,

2) Materials used in contact

and lastly, the prority, to dissipate the heat out of the case. iMacs are terrible for such purposes unless you remove the heat-generators.

One surgery I have performed on a PowerBook was to remove the HD. It was cooled considerably.

The other way is to use a Peltier. I am hesitant to recommend this route. Since you have to be 100% careful at all times and knowledgeable.

Macs are costly.......

[The Godfather]

No external monitor needs a fan, why does the iMac monitor need one? Is it because it is cheap $h|t? There should be a way to skip the air from circulating the monitor and cool only the electronics at the bottom of the monitor.

[TheDoctor]

Actually, the old Apple Portrait Display (black and white full-page monitor) DID have a fan installed.

[Ca$h68]

No, its cuz the computer is built in. Hence the monitor (or computer) needs a fan. And more air through the monitor means more air through computer = cooler chip.

Ca$h

From your comment, you seems like a beginner in OC.

In physics, heat does not disappear. It transfers somewhere else (The cold) & it's constantly happening around us. This law is universal.

What you need to know is, air blow towards the chip.

1) Yes, the chip is cooled. Hot-air is blowed-off the surface. Where does it go?

I am sure your logic board wouldn't like the heat either.

[Ca$h68]

yeah. kinda. I made it so the hot monitor air was NOT blowing on the chip. I think you have it mixed up. I thought that if I flipped it so it blew upward, it would help the air movement, since the air in the monitor compartment is moving upward anyway. So if both the fan and the convection were going the same direction, I'd think it would have worked better. But it lacked cooler air on the rest of the internals...so... I need more fans basically.

Ca$h

Btw. mlonh is asking Members opinions on getting rid of that Dragonlance creature. And a lot of people said yes to it so the wichy washy stupid turncoat lamer should be kicked out soon. (Hopefully)

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[wlonh]

hey that thread was more of a mind to get him to behave, and it's an old thread now

looks like it worked too

It's been a long time since I [mod]ed my iMac Revision B. Sold it last fall.

All I can remember is the fan need some "hack" work. Replace it with better ones. Panaflo would be nice. Approximate size is probably 80mm or 92mm ish.

The best way for iMac is,

1) Remove the internal CDROM and HD. Replace the mezz with a Formac TV/SCSI adapter. So you can watch TV & going for external SCSI HD. A much better solution ( Get a Atlas 10K and see it scream ).

2) You would have all that free space for heat dissipation. Method? Brainstorm it out.

[Kozmik]

Hey Ca$h, if you hate the iMac so much and needed to improve it so much, why did you buy one in the first place? Don't complain about things when you made the decision.

From my experience with Ca$h, it's not that he hates his iMac, it's just some of the parts that annoy him. Previous posts have said that he enjoys the MacOS, and the form factor of the iMac, but he'd like to improve the internals a bit, which he has. In the iMac forum, he has expressed his love and adoration towards his new FrankeniMac, and how it lulls him to sleep at night. I tend to agree with some of the points that he makes, the graphics chip in the old gen iMacs is nothing to write home about, i have to suck it up and deal, b/c i don't have the money to purchase a new computer yet, so there. Unlike some of the other yahoos on the board, Ca$h has done something about his situation instead of just saying "why can't apple spend millions of dollars to make a machine that i will enjoy that they pass out for free" thank you.

[Ca$h68]

Right. I dont hate my iMac. However, I think it is UNFAIR that the "consumer" macintosh comes with such a blatently pathetic video card. I mean, I'm definatly a consumer, and there is no way I could afford a G4. So iMac was pretty much the only choice for me. And I'm also a consumer who likes playing games. Well... iMacs suck at games. Thats what I wish they would change. The video card blows, the fact that the sound circuits leech off the CPU, the ethernet does too, all these make it suck as a gaming machine. However, if APPLE were to correct this, iMacs would be the ultimate gaming machine. They'd be portable, fast, easy to set up, built in monitor, and semi-upgradeable. One PCI slot, thats all I ask.

Ca$h

[suhail]

Yup I agree, iMacs should have replaceable video cards, and upgradable CPUs.

Especially when Apple is bragging about 'Macs for games'.

Apple can't be expecting people to buy new iMacs every year.

Apple doesn't have to say that iMacs are upgradeable (to avoid law suites), they should make some of the iMac components replaceable to allow after-market upgrades.

iMac Rev-A was somewhat upgadeable, but that was hacked off in Rev-B!! Whhyyyy???

Rev.A & B are very similar, the most upgradeable of all iMacs. The difference is the Graphix chipset. Rev. A has the older Rage. Processor can be upgraded with a swap (Rev.C, D possible?) or a Newer G3 466Mhz.

These machines lacks firewire.

iMacs' target market is for newbies, kids, and PeeCee wannabes. It was never meant for serious usage. Like a baby diaper, you change it frequently and daily. It serves the intended purpose.

[Evinyatar]

I thought the bus speed was different too: 66MHz on Rev A and 100MHz on Rev B/C/D. But I'm not sure.

[wlonh]

this looks like a good enough place for this: http://www.info.apple.com/applespec/applespec.taf

according to apple spec all have 100MHz busspeed

[Kozmik]

iMacs up until the 350s and DVs had a 66MHz bus speed. I'm sure of it. By the way, I use my iMac for serious use, because I could not afford a G4 and all the peripherals I wanted. Whereas with an iMac DV SE, I easily could afford all that good stuff.

[wlonh]

then why does applespec say 100MHz?

hey i thot 66 was the case for the first 2 revs anyway, whatever

[This message has been edited by wlonh (edited 06-04-2000).]

[Kozmik]

Find an old iMac and run GaugePro on it. That tells you the bus speed, doesn't it?

[Ca$h68]

1st gen iMacs have 66mhz bus speeds. I dont care if Steve Jobs even came out and told us that they have 100 mhz buses... it just aint true.

Ca$h

[sine -''-..-]

They are 66mhz, the ram is 66mhz SO DIMMs
so...

Pardon me,

but this is so stupid. Why sit here arguing about whether flipping the fan one way or the other is going to cool the iMac better or worse on theoretical grounds. It's all just theory. Anyway. What I'm trying to say is why doesn't somebody just get a darn thrermocouple and stick it on the processor. Turn on the computer. Let it reach steady state. Measure the temperature. Flip fan. Repeat.

???

I'd do it except I don't have an iMac.

For that matter, why not at the very least run a few trials and use GaugePro or the equivalent to read off the junction temperatures.

(And then argue for hours about the results)

-Coyote

[Herr Newton]

Just don't reverse the polarity of any cooling fan---i.e., connect what was originally positive to negative and vice versa. Why? Doing so reverses the rotation of the fan and fans just don't work when run in reverse.

[Ca$h68]

UH... HELLO!?!?!?? MCFLY!!!! WAKE UP! Read the FIRST post in this thread. Read what happens. The rest of the iMac burns up. Hence, who gives a flying **** how much cooler the processor is running when your CD rom drive is melting. ARgh. People annoy me sometimes. >

Sorry, bad mood right now, and you get my venting.

Ca$h

[Ca$h68]

PS: That post was directed towards Coyote.

[slboett]

Why not just add a second fan at the top to draw more air through? Jeezes, this ain't rocket science folks...
If you use a thermocouple, you need to test all heat-sensitive components, not just the processor!

Scott