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 Post subject: 80mm to 60mm fan adaptor to reduce dead zone on SLK-800
PostPosted: Fri Dec 13, 2002 4:24 am 
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If you use a adaptor such as a 80mm to 60mm (rounded type, seen square ones too, I think less effective), surely this will reduce the deadzone in the centre of the fan because the air is now being compressed together. I noticed in the Socket A heavyweight shootout there was a suprising turn in results where the SLK-800 was less effective using a panaflo 80mm fan at 5v. I just wondered using this adaptor, whether it would reduce the dead zone and effectively provide more airflow diirectly over the cpu die.

Just a suggestion.


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 Post subject: Links for adapters?
PostPosted: Fri Dec 13, 2002 6:39 am 
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Hello:

Where can we see what these adapters look like? :?:

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PostPosted: Fri Dec 13, 2002 10:36 am 
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http://www.thecoolingshop.co.uk/tcs/comersus_listcategoriesandproducts.asp?idCategory=36

just click on more info to see what they look like.[/url]


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PostPosted: Fri Dec 13, 2002 7:52 pm 
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I don't know if it completely applies here, but I've had first-hand experience with these 80-60mm adapters (actually the exact same one that ex2remember linked above).

The problem with these is the back-pressure that is generated when trying to force the air through the funnel. A whole lot of fans don't react well to back-pressure, Panaflos being one. You end up having to put a more powerful fan on top of the adapter to overcome the loss of airflow due to the back-pressure. When you're all done you end up with acceptable cooling but at a higher noise level than what you started out at.

This seems to be the general consensus among people who've tried these adapters on CPU heatsinks.

YMMV!

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 Post subject:
PostPosted: Wed Dec 18, 2002 7:22 am 
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Well, using a 80-60mm adapter on a heatsink intended for an 80mm fan would create backpressure, and backfire in the results. Yet, what if one used a 120-80mm fanadapter? Would the results outpace the backpressure?[/b]


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 Post subject:
PostPosted: Thu Dec 19, 2002 6:32 am 
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lazygun wrote:
Well, using a 80-60mm adapter on a heatsink intended for an 80mm fan would create backpressure, and backfire in the results. Yet, what if one used a 120-80mm fanadapter? Would the results outpace the backpressure?[/b]


No matter what else it would do, it would add at least 3" to the height of the HS. On many cases this plus the height of the SLK-800 would end up being almost as high as the case is wide. And I also wouldn't want another 3" of added weight putting even more leverage onto an already heavy and high SLK-800. C-raaackk!

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PostPosted: Thu Dec 19, 2002 7:09 am 
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I remember reading on a fan manufacturer's web site somewhere, about the phenomenon of 'blade stall'. It happens at low RPM's with too much back pressure. Basically, you get a breakdown of the directional flow across the fan blade surfaces, just a bunch of turbulent swirling instead, which kills the airflow much worse than the reduction you would expect simply for the given low RPM and back pressure combo. I know that Panaflos are poor at back pressure to start with, and the turn around in that test happened between 7v and 5v, where the Panaflo makes it's biggest incrimental performance drop. Add to that the thinfin design of the SLK-800, = high back pressure, and I think we witnessed a blade stall effect. The AX7 has much wider fin spacing, and I bet it managed to not force a stall condition, so it kept up where the SLK crapped out. The only way to really tell would be accurate airflow measurements, which would tell us what's really happening with the airflow vs. heatsink vs. attempted fan input.

Given all that, I bet a 80-60mm fan adaptor would just cramp the Panaflo even worse, and you might get almost no air at all. I wonder about mounting the Panaflo a little ways above the SLK, maybe leaving a ½" gap to let the air keep moving. You might get back more than you loose by preventing an all out stall. Another apporach might be to cut ½" off the top of every other fin, to open up the top end of the SLK without loosing too much fin area.


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 Post subject: 120mm adapter?
PostPosted: Fri Dec 20, 2002 12:15 pm 
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I know this is slightly off topic, but...

What about using a 80-120mm adaptor sucking INTO the case, with an undervolted 120mm fan? Would the lowered pressure behind the fan create a vaccuum of more noise, or is there enough space in the case to prevent a large difference in pressures?

-C


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