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Some responses to my Cohesive Air Cooling Article

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Inactive Moderator
Feb 13, 2001
Twin Cities
Hi Gang;
I've gotten some emails regarding my single blower cooling solution ( http://www.overclockers.com/tips461/ ) and I thought it would be good to share them with you all.
Could you mount that centrifigal fan to the rear fan case opening and duct airflow over the heatsink? This would allow you to use the stock case side cover and hang the big fan out the back, keeping the case upright.

Thanks for the email Anthony. Actually, the only reason I didn't use the stock cover was because I wanted to make sure my idea would work before I cut a hole in my cover. I have since cut my cover and installed the blower on it. It actually looks nice, at least to me. The rear fan opening, at least on my mid-tower case is positioned above the heatsink and with the exhaust from the blower being so straight, the majority of the air would blow over the top of the heatsink. Perhaps some deflecting device could redirect the air downward into the heatsink, but then you impart a lot of turbulence to the airflow pattern and lose the cohesiveness.

Your welcome Marcin. It was fun experimenting on it.
I read your article on overclockers.com and your use of a centrifugal blower to cool your computer. I went to grainger.com to try to find the fan but I could not. If you could please send me a model number or direct link, I would really appreciate it. Thank you.

Your welcome Jeff. The blower is made by Dayton and the part number is 2C646A
Just read your PC cooling article - what a project and
well done. I have used the following from PC power &
cooling and got pretty good results (25F improvement)
and did'nt have to do as much surgery !

Keep up the good work !

Thanks for the tip Bbp98
Thanks for the great article on cooling. I haven't laughed this hard in a long time. You did a great job describing your trials.

Thanks for the feedback Dennis.

Since I wrote the article, I have increased the effectiveness even more by placing a duct directly below the fan opening in the cover. It extends down to and stops just above the top of my heatsink. The duct is 3 inch square aluminum tubing 1/8 inch wall that I got from the local Aluminum supply house. It helps maintain the concentration of airflow until it can hit the heatsink. It also reduced the sound of the rushing air (not an unpleasing sound) a little bit. It reduces the thru-case flow a little bit, but the system temp is still the same as room temp.
If you go with this setup and choose 7V as your operating voltage for the blower, do not use the old trick of placing the plus lead on the system +12 and the minus lead on the system +5. The low impedance of the motor looks like a short circuit until it spins up and when you fire up your PC, the PSU will shut down immediately, thinking something is shorted. I would be glad to answer any other questions about the article. Post an inquiry here, in the cooling section, so all can benefit from it. Check out my new speed in the signature!

Another email with a good question.
I really enjoyed your article on the cfgl blower fan.
I have 2 Nider "squirrel cage fans in my tower case mounted on a piece of acrylic which sits behind closer to the front of the case) the motherboard. Its screwed into the case on those little metal square brackets that the mb sits on (Addtronics 7896 case). Air comes in through the front of the case (3 fans) and is then accelerated by the 2 blowers across the entire mb, thus cooling it. The system temp is around 25C. But my cpu temp is 37C with both case side panels on (34-35C with one off). Your method sounds ideal to cool the CPU further. Mounting it on the side panel with some anti-vibration pads may work. (similar to what you've done). I think MDF or plywood or dense plastic or rubber is probably enough. Your thought would be appreciated. I'm sure you've had time to think about "tweaking" your design. Thanks for the great tip.
Thanks for the input Joe and I looked at those Nidecs a month or so ago, when I was pondering this approach. The total cfm was a bit low for my idea of a single blower solution, but I like what you've done with them to enhance case circulation. Yes, when I moved the blower from the 3/4 inch particle board, to the sheet metal cover, there was definitely an increase in tympanic effect (drum head). The thin metal propagates a low frequency rumble. Though not bad to start with, I reduced it to almost inaudible with some 1/4 inch square aluminum rod attached to the inside of the cover in an X pattern, with a thin strip of rubber gasket material between the rods and the cover. Rubber dampening pads glued to the inside of the cover is an excellent idea also. I have some of that stuff. Kind of an orangish, 1/4 inch thick, high density rubber. I think it is silicone based, but not sure. Glad you enjoyed the article

Great article Hoot. From your description of the noise, it seems like a good way to reduce system noise and improve temps at the same time. My Celeron 600 is cooled by a 7000+ rpm 60MM that is loud enough. But add to that a Sunon 120 and the 2COOLPC +, a 92mm exhaust a slot cooler and a 60mm sucking the drives heat... well you can imagine. It sounds like an old fashioned drink cooler on a 100 degree day. Since my system is located in the living room, noise reduction would win kudos from the wife and kids. If you come up with a solution for the "squeak" please let us know.
I should have mentioned that the squeak is a non-issue now. Once the brushes got broken in, it is all but inaudible sitting two feet from me. Interestingly enough, I found the squeak was being propagated out of the motor housing by the two power leads. I know that sounds weird, but by repositioning the leads, which pass through a rubber grommet in the motor housing, along with the brush break-in, you have to listen for the sound to notice it is there.

Great article Hoot, I am now thinking about getting something like that to blow through my radiator and case to improve airflow.
It would almost be a waste of money to only use it for cooling your radiator. One of the justifications for the cost was the fact that this one blower could replace all the fans, including the HSF. I'm sure it will perform well as a radiator cooler though.

Not sure when, or even if I will make the move to a full tower yet. For my hardware compliment, the mid-tower has been a good compromise so far.

Some more emails
I really like that centrifugal blower idea! I am gonna buy one from grainger online and see how I can get it to work. I am gonna try to integrate it somehow so it is somewhat inside the case instead of this big unit just sticking right out of the case. Will the blower work the same as far as effectiveness if it blows from the inside out?

Thanks Marty. I'm not sure how it would perform under that scenario. It's so big, I can't imagine it inside a case. Something to consider is the heat the blower gives off. At full speed (12V) the motor housing is uncomfortable to touch.
Is that a a brushed blower? If so, it's not good for your computer. It can cause electromagnetic interference and it usually has a short lifespan. Besides these quirks, you have a pretty good set-up for your system cooling. Congrats!

Thanks Fusi0n. I thought about that and brought an RF Spectrum Analyzer home to check the radiated EMI/RFI. It was in the noise floor, which was more than I can say for the RFI generated by the computer itself. As for conducted EMI/RFI, I had already put a ferrite choke on the leads, as well as a capacitor. The fact that it is located outside the case probably negates any impact upon the data cables inside. I have not experience any anomalous data corruption so far. Checking where the leads connect to the 4-pin plug from my PSU with an oscilloscope, it was pretty clean. Yes, brushed motors do have a shorter life-span than non-brushed ones. Running it at a lower speed like I am may improve that scenario. Time will tell. The brushed blower on my truck heater has run for 10 years now and I put as much time on the truck as I do on my PC. Also, my PC room environment is a lot less hostile than my trucks, given the weather here in Minnesota.

I am working on a speed controller that utilizes an LM-338K 3-Terminal adjustable regulator. This is the hefty "Big Brother" to the LM-317. It is rated for 5A continuous service. Once finished, I will publish the results.

Great work Hoot. I say we honor your cleverness and innovation by calling the Rectangular Hole cut in the case to accomadate the blowers' output the Hoot Chute.
There goes your performance down the Hoot Chute :D
Good one Slake. I needed a good laugh this morning.

Perhaps you could post some pics showing all of the electronic parts you connected to the blower - the molex, the capcitor, the ferrite choke. A little info for those who are not so electronically inclined would be nice as well :)

Also, how do you get the fan down to 5V? Can it go lower?
I submitted a follow-up article that will hopefully appear in a few days. The ferrite beads and capacitor are out, due to using a 3-terminal regulator to vary the voltage driving the blower. The regulator isolates the blower side from the system side of the 12V supply. There is an enhancement to performance as well as wiring pictures. Oh yes, what it looks like in the final assembly.

Very nice job! It seems that this is about as good as it gets for air cooling. Lets just hope that the next generation of AMD's don't need such extreme measures to dissapate heat.
Let's have a big Amen for brother Ken! I look forward to the day when all of these extreme cooling measures are just a fond memory.

I'm new to this site, so please forgive me if this question is stupid.

How long does it usually take for a follow up article to be posted?
I read that article, and was quite impressed with the ingenuity of the solution. I guess that I never read the author's name, but that is quite unlike me.

Great work, and I'm impatiently awaiting the sequel.

Magistrate (May 21, 2001 08:00 p.m.):
I'm new to this site, so please forgive me if this question is stupid.

How long does it usually take for a follow up article to be posted?

Joe has to compile it from MS Word to an HTML format. He has lots of articles, that he and other authors submit. Give him a few days and I suspect it will show up.

I haven't implemented a filtration system yet as I was waiting for the "dust to settle" on the project. ;D

The air intake maw has a ring around it, with retaining screws, that can be used to mount some form of filtration media. My house has an effective Electro-static air scrubber on the furnace, so I'm pretty lucky. I only dust about once every 6 months. Realistically, I will look at some different media in the next week or so.


How hot is the motor @ 7V??? and would it work if u use 5 V??? It looks like a VERY promising concept IF they could come up with a smaller fans, the current one is just too HUGE!!!