Found DOS card in a boxed 6115 CD

retr01

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Noctua fans! :)

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retr01

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I've finally joined the club :)

6100/66 DOS Compatible just like when I was a kid...the nostalgia is hitting me pretty hard at the moment :)

Fun! :D (y)

I do want to try to improve the airflow on the left half of the system where both CPUs are currently having a heat orgy. I did put a 40mm fan inside the PowerPC processor's heatsink that kept it cool to the touch...until I installed the DOS card. Now that whole half of the chassis is roasty-toasty. There are ventilation slots cut into the bottom of the case under where the HD used to be. I wonder if I could slide a low-profile exhaust fan under there since heat doesn't tend to go downwards by itself. I'm sure those vents are intended as inlet, but the PSU fan doesn't create enough pressure to pull any meaningful amount of air through there IMO. Or maybe using that fan to pull air into the case would work better...not sure if it would overwhelm the exhaust capabilities of the PSU fan though...

Yes, if there is room and venting at another location, by all means. You can use this adapter to power the second fan. The thing is, the load on the PSU you may want to consider. Also, ensure the second fan is blowing in the right direction. It usually has air running from the front, front bottom, or the sides to the back, depending on the case. If you were to add a second fan blowing in another direction out, then it might not be as efficient.

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KennyPowers

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The thing is, the load on the PSU you may want to consider
I'm not too worried about that since I'm no longer powering a hard drive. I checked the voltages under the current load with the PC running and they're all still at spec. Another low amperage 12v fan shouldn't be a problem.
 
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KennyPowers

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Hey @KennyPowers, I looked at the PPC 6100 case and realized maybe only top vents in the back. Is that right? No other ventilation?
No top vents. There are bottom vents under the plastic under the BlueSCSI in my picture (where the HD used to be), and then bottom vents under the PSU that the PSU fan exhausts out of. Then there are a few open "seams" in places where negative pressure could pull air in too (mostly at the rear card slot opening). But ya, it's a terrible case for airflow and the two processors are literally directly on top of each other with maybe an 1/8" between the heatsinks. So *maybe* a slim fan could go over the intake vents that are under the HD bay and flow some cooler air towards the CPU sandwich...

On the other hand, it was designed to be used this way and has been for 27 years, so maybe it's ok. I just don't like how toasty it feels.
 

retr01

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No top vents. There are bottom vents under the plastic under the BlueSCSI in my picture (where the HD used to be), and then bottom vents under the PSU that the PSU fan exhausts out of. Then there are a few open "seams" in places where negative pressure could pull air in too (mostly at the rear card slot opening). But ya, it's a terrible case for airflow and the two processors are literally directly on top of each other with maybe an 1/8" between the heatsinks.

Oh boy. :oops:🥵🤒♨️ That could develop problems down the road. Not much to tinker that, yet I wonder if can figure out widening the gap between the processors. Hmmm.

So *maybe* a slim fan could go over the intake vents that are under the HD bay and flow some cooler air towards the CPU sandwich...

Yeah, a slim fan, like this but around 60 x 60 mm?


There is another type of fan for high flow:

 

KennyPowers

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Oh boy...
The only way to get more space between the heatsinks would be to put a different style heatsink on the 601 because it is the taller of the two...the 486 heatsink is already pretty thin as you can see in early pictures in this thread. Mounting a different heatsink would be tricky though, and the 601 is too fragile for me to be comfortable experimenting with like that. Right now I have a little 40mm fan set inside the 601 heatsink blowing down (it's flush with the top of the heatsink and sits in the center "cavity" with space under it). That was keeping the 601 cool to the touch until the 486 was installed. With the DOS card in there, the entire metal back of the card gets hot to the touch eventually, even with the lid off (I wonder if the metal lining of the lid would act like a big heatsink for the card...lol).

I saw someone over on 68kmla use a blower style fan like that over the intake vents to direct fresh air towards the CPUs...wonder if that would make a noticeable difference. Smaller fan will be louder though, and any air pulled in from that spot by a traditional fan would have nowhere to go but towards the CPUs anyways...
 

retr01

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The only way to get more space between the heatsinks would be to put a different style heatsink on the 601 because it is the taller of the two...the 486 heatsink is already pretty thin as you can see in early pictures in this thread. Mounting a different heatsink would be tricky though, and the 601 is too fragile for me to be comfortable experimenting with like that.

Yeah, gotcha. A small slim fan may be inserted in that scary-looking metal "fence" over the PPC 601 CPU. That's an idea with 3D printing an adapter.

Poor CPU must look scary from a perspective with the evil Microsoft-backed PC stuff breathing right above it, straight from a scene in Lord of the Rings, Ghose Rider, or the second movie of the Bill and Ted's Excellent Adventure series. :sneaky:

I wonder if the metal lining of the lid would act like a big heatsink for the card.

Yes, with cramped quarters in that case. I wonder what folks did back in the day to address that, given the Apple III fiasco that the case did not have enough ventilation.

I saw someone over on 68kmla use a blower style fan like that over the intake vents to direct fresh air towards the CPUs...wonder if that would make a noticeable difference. Smaller fan will be louder though, and any air pulled in from that spot by a traditional fan would have nowhere to go but towards the CPUs anyways...

Do you know where on 68kmla? Link?
 

KennyPowers

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Do you know where on 68kmla? Link?
 

retr01

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@KennyPowers, note @YMK's suggestion in post #17 of that thread:


That is a good one. Have you considered that? :)
 
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KennyPowers

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I'm sure it won't at 5 or 7 volts.
Ya, I suppose I could try running it off the 5V line and see if it's effective...should be about 1W that way if my math is right. Startup voltage is 7V though. I'll figure something out...
 
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