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Mac SE without a fan?

While it is true that you have an SE whereas I have an SE/30, the body is still the same (i.e., no vents on top like the Plus and earlier). And I too removed the internal HD in my SE/30 to decrease the heat. Even so, I still feel HOT air blowing out the back (via my internal fan). Therefore, if you have no fan and no vents on top, where does that heat go? Answer: only a small amount leaks out and the rest remains inside your Mac, gradually making it hotter and hotter until one of your components goes, taking the rest of the machine with it.

So how does one resolve this problem? Easy. Just replace the noisy fan with a quiet one. In my case it was easy. I already had a stock "boxer" type Elina fan in the SE/30 so it was easy to choose another 60mm fan from Silenx to give me about the same air flow but at 1/10th the noise levels. If you have a cylindrical fan, your mounting bracket may not accommodate a boxer fan easily so it may not be an easy fix like my Mac. But I do know that some SE's came with a boxer fan so those models are easy to swap it.

Simply put, don't remove the fan and run your Mac 24/7. Indeed, I wouldn't run it more than 3 hours straight in that condition. If it had vents on top, I would say go for it, as the heat would rise up and out those vents. But for SE's and SE/30's, that heat will not escape, I am sorry to say.

Hope this helps.

 
It does, and I am considering replacing the fan as well, but also the SE/30 of course has a 68030 and the SE has a 68000 which I assume has to run cooler.

 
It does indeed run cooler. But think about it; the old 8MHz Macs with no fans had hella ventilation, and they still suffer the ill effects of overheating. Your SE has none of those vents, so with no fan, it would suffer worse. I'd just get a quieter fan if it bothers you that much; don't run it for any real length of time with no fan.

In general, if it has a fan in/on it, it's prolly meant to have it there for some reason or another.

 
Probably the best thing to do is try it out. Do what JDW did first: remove unnecessary components (the hard drive is the only thing that comes to mind), but leave the fan on and see if hot air comes out. If so, that's a bad sign.

Next step, stick some sort of electronic thermometer into the case and monitor the temperature. Do this with and without the fan, clearly monitoring it more closely with the fan removed. If there's a substantial difference, that's a bad sign.

There is some sort of metal shield on the bottom of the mainboard. Removing that may improve air circulation from the lower vents, using convection cooling just like in the Plus. It may work, because I'm guessing that the vent for the fan on an SE will constrict the airflow less than the top-mount vents on the Plus.

Also consider the temperature in your house. The rate at which heat is dissipated through conduction depends upon the temperature difference between the inside of the case and the outside of the case. Convection will depend also depend upon that temperature difference.

 
As a practical matter JDW is right on.

That said, the SE has a sizable vent in the rear, vents on the bottom and the entire front of it is a vent. So, in theory it will work the same way as the original compact. How efficient it will be, especially running 24/7 is another matter. With no hard drive and performing no more complicated calculations than displaying a clock, certainly the heat generated should be minimal with or without a fan. Perhaps even removing all but 1MB RAM as well.

I would be interested in a thermometer test to see where the mean temperature inside the case would be, compared to the Plus (the fan should be completely removed so as not to block the vent at all).

The logic boards use similar low-power RAM cards. The SE supposedly has more robust power board components and a more efficient redesigned self-contained universal power supply. Theoretically, these more robust components should stand up to higher temps than the Plus. The question is: how much higher would the internal temp be in a stripped, fanless SE and would they be tolerable?

 
While Dennis is correct, most of us do not wish to do that.

To provide a small amount of further information for Mac128, even when my stock Elina fan was in my SE/30 (which moved slightly more air than my existing Silenx fan replacement), if I left the computer on for a couple hours and then touched the very top of the case with my hand, it was very warm. And again, this is with a fan in there, pumping out hot air continually. The reason is because the amount of heat flowing up is still faster than the fan can pump out. And so the residual heat flows up into that pocket at the top of the case and stays there. I've not left my SE/30 turned on 24.7, but I can imagine that the top of the case would get even hotter if I did leave it on that way.

Remember that the fan on back is fairly low down vertically on the machine. It's not right up there at the top of the plastic. But anyone can do a test, with or without a fan on the SE-series machines. Just turn on the machine and feel the top, then re-test with your hand every 30 minutes for a few hours. You will feel that the top heats up.

"Yes, but isn't it true that the electronics are at the bottom and the fan would cool them sufficiently such that they won't overheat." Well, if you have a fan, then yes perhaps. But again, even with a fan I yanked my internal drive because I have a Diimo 50MHz 030 card along with an Ethernet card that produce more heat than a stock machine. The 7200rpm hard drive was always too hot for me to touch, and it alone became a heat problem, resulting in my removing it. But if you don't have a fan, all that heat up there in that Heat Pocket is going to build at a fast rate, faster than what would be pushed out the little fan hole in the back, so your overall machine is going to get hot, very hot, in a couple hours.

So to the individual who opened this thread I would say this, just test it. Kill the fan and turn it on a few hours and touch your machine and let us know how hot it gets. We can then use common horse sense to make a decision on what you should do. (But I can tell you right now, you really need a fan.)

 
Thanks everyone for the great discussion/answers. I'm going to take out the hard drive and boot it up with the fan, and see how hot the air is (subjectively) coming out the back.

 
I think what JDW is saying is that without a fan you have a Macintosh SE Oven:




To provide a small amount of further information for Mac128, even when my stock Elina fan was in my SE/30 (which moved slightly more air than my existing Silenx fan replacement), if I left the computer on for a couple hours and then touched the very top of the case with my hand, it was very warm.
Certainly everything you say is correct. What I would add is that my MacPlus without a fan is also extremely warm if left on for a few hours. And don't forget the SE/30 68030 also produces a lot more heat than does a 68000 chip. I would never run a 68030 without a fan. However, given that the 68030 PowerBooks were basically ventless and fanless, most of the heat must be attributable to the power supply & analogue video circuitry in the compact. But, I'm not sure the heat would get trapped exactly. When the air in an enclosed space heats up, it is naturally convective. Meaning the hot air is going to circulate inside the case and exit the most expedient path, no matter how small the opening. Whether this is enough in a striped down SE needs to be tested. A couple of hours running this way shouldn't hurt it and simply check the temperature of the top of the case. It would be nice to compare it to the temperature of the top of a Plus (not over a vent, but the case temperature between the vents). A check between the SE case temp with a fan and without would also be helpful. Knowing the difference between the two SE configs would allow a lot of good speculation about the rated tolerances of the components.

The final word of course is, that heat shortens the life of anything. The best way to run any computer is with adequate ventilation with refrigerated air being blow into it. Many Macs I've seen in recording studios back in the day when the monitor cable length was finite, had to be in the same room. But the fan was intolerable noise. So they were encased in iso-boxes which with no ventilation, totally negating the effect of the fan. An insulated A/C conduit was then attached to chill the air and another air-return ran out of it. Those had to be some pretty happy Macs.

Applied to a fanless Mac, if located near an A/C vent, running a feed into the bottom of the Mac would effectively speed convection and expulsion of hot air and probably keep it pretty cool. Then again it would take away from some of the charm of a clean unit sitting on your table. You might be able to feed it though the back of the PDS card knock-out and down inside, though.

 
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