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Open Case Without Fan

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dvanaria

Experienced Member
Joined
Apr 11, 2013
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110
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Denver
One of the only things I don't like about running older PCs (386 and 486 era) is the noise of the fans. I like playing games with the sound card hooked up to speakers, but the fans are often so loud in these types of cases it kind of takes away from the fun a bit, even with a tower case sitting on the floor (and I like building systems with the older, desktop variety cases that you sit the monitor on top of).

Does anyone know if its safe to disconnect the fans in these systems and just run them without this extra cooling? I would be running software and games that wouldn't be pushing the cpu to its limit most of the time. I've also considered running the computer without the case lid on (though of course the monitor would have to sit directly on the desk for desktop-type cases, if the lid isn't on).

The only thing I'm worried about is running the cpu too hot and causing either damage to the cpu itself or some other part of the computer.

Thanks for any help/advice.
 
Build a system around a laptop version of the 386/486 and you will need minimal cooling. Install a slow big fan and everything is kept under safe temperatures while also being quiet.

Post details of specific cases, CPUs, and fans and perhaps more specific suggestions can be offered as to how to quiet the system without causing overheating.
 
The problem is the PSU is usually the thing with the fan. Most everything else in a 486 machine doesn't dissipate enough to need one.
 
I found the major noise factor on 486s to be the tiny CPU fans placed on undersized heatsinks that shipped with DX4 models. Lower power CPU and bigger heatsink allows the whiny fan to be removed. Attaching other fans to the case can allow the PSU fan to run at lower RPM and make the system quieter.
 
My Tandy 1000SL came with a wind-tunnel hurricane-force fan that produced way more noise and air flow than was necessary, so I opened up the power supply and rewired the fan to run on 5 volts instead of 12 volts. The result is a fan that runs near-silently and still provides adequate airflow to keep the system cool.

If 5 volts isn't enough, you can also wire the fan across the +12 volt and +5 volt leads, giving you 7 volts (12 minus 5).
 
krebizfan said:
I found the major noise factor on 486s to be the tiny CPU fans placed on undersized heatsinks that shipped with DX4 models. Lower power CPU and bigger heatsink allows the whiny fan to be removed. Attaching other fans to the case can allow the PSU fan to run at lower RPM and make the system quieter.
Click to expand...

I run my AM486-120 fanless. I used an old AM2 heatsink.

I checked the CPU surface with an infrared thermometer after hours of full load and it doesn't exceed 50-52c
 
smeezekitty said:
I run my AM486-120 fanless. I used an old AM2 heatsink.

I checked the CPU surface with an infrared thermometer after hours of full load and it doesn't exceed 50-52c
Click to expand...

All of the AMD 486DX4 chips I've seen say "Heatsink and fan req'd" on them, but many of the AMD 5x86-133 upgrade modules used the "laptop" version of the chip which only needed a heatsink:

81ufx-ftYCL._SY355_.jpg


Most Cyrix and IBM (rebadged Cyrix) 486DX2/DX4 and 5x86 chips came with a heatsink affixed and did not need a fan.

Cyrix_Cx486DX4-100GP_pinkie.jpg
 
All of the AMD 486DX4 chips I've seen say "Heatsink and fan req'd" on them
Click to expand...
Mine does too. But I assume they are assuming you would use a small heatsink.
This heatsink is designed to dissipate like 90w with a fan so it should be able to handle 4.3w without one (and it seems to)
 
All CPU's I know of until the P1 MMX that have a small heatsink + a fan can safely operate by replacing them with a larger heatsink.

In fact many OEM pc's of known brands were shipped with an oversized (for that time) heatsink without any fans. I'm not aware of a single chip until the MMX's that wasn't shipped at least from one manufacturer with a fanless cooling solution, so I'd say this is possible as long as you use the correct heatsink.

But as it was said earlier, most of the noise comes from the PSU
 
I can echo the comment about the PSU being the biggest noise problem as far as fans. Fortunately it is possible to replace it with a silent newer one, with the use of an ATX-to-AT convertor. My 486 has one fan on the CPU and one in the PSU. The CPU fan is almost silent, though it is a dx2 not a dx4.

But for me, the biggest sound issue is the CD drive. On newer systems I am so used to copying over the entire disk, that I rarely hear the CD drive spin up. My 486 has to spin it up and down fairly frequently.
 
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