Dead Points

Devil_H@ck · 06-20-2003, 04:49 AM

I was searching for more info about a fan's dead point, but I couldn't find any.
Maybe you guys could help me?

I was just wondering how far away I should position my fan from my Alpha PAL to reduce the dead point to a minimum.
Is there any formula for this?

JSimmons · 06-20-2003, 06:42 AM

I go by the size of the center hub. The larger the center hub, the further away the fan needs to be to eliminate the deap spot. Of course, few cases provide enough room inside the case to allow much more than one inch, so that's pretty much what everone uses.

If you can mount the fan *outside* the case, you get, of course get more distance. I have a rad with a pusher/puller setup, and the pusher fan is 1-1/2 inches away, and the puller is about two inches, but the puller fan is mounted outside the case.

Check out page 4 of the watercooling url in my sig.

Devil_H@ck · 06-20-2003, 10:46 AM

Hm, I'm using an Enermax fan with the large Alpha PAL P4 heatsink.
Would there be a large difference in temperature if I move the fan 2 cm?
I can move it more I think, I've got an AOpen HX08.

JSimmons · 06-20-2003, 12:46 PM

I don't think you'd notice much of a change by moving the fan away from a heat sink unless you had a duct that guaranteed the air was bing pulled over the fins of the sink.

Devil_H@ck · 06-20-2003, 01:40 PM

Ok, nevermind then.
Thanks anyway.

Yo-DUH_87 · 06-20-2003, 03:26 PM

Welcome to procooling, bty

hara · 06-20-2003, 04:45 PM

Welcome!

First of all, in what direction is the fan blowing air?

By spec, your heatsink should have the air sucked from it instead of blowing.

If that's what going on then by moving the fan will in fact reduce the deadspot (since air sucked has a laminar flow) but don't ask me how much and if performance will vary.

If your fan is pushing instead of pulling (like any other hs) than by moving the fan backward, performance could decrease since the airflow in front of the fan is turbulent. Heatsinks work well with turbulent flow but moving the fan back will not only shrink the deadspot but also reduce the airflow through the heatsink.

What I suggest you experiment with is to get rid of the shroud and mount the fan the other way round (i.e. Blowing into). Some people reported better temps this way.

Devil_H@ck · 06-20-2003, 05:08 PM

Hm, I think I'm letting it blow, not sure though.

06-20-2003, 04:49 AM	#1
Devil_H@ck Cooling Neophyte Join Date: Jun 2003 Location: Belgium Posts: 4	Dead Points I was searching for more info about a fan's dead point, but I couldn't find any. Maybe you guys could help me? I was just wondering how far away I should position my fan from my Alpha PAL to reduce the dead point to a minimum. Is there any formula for this?

06-20-2003, 06:42 AM	#2
JSimmons Cooling Savant Join Date: Apr 2003 Location: 4-sided room with an exit going east, and an exit going south Posts: 392	I go by the size of the center hub. The larger the center hub, the further away the fan needs to be to eliminate the deap spot. Of course, few cases provide enough room inside the case to allow much more than one inch, so that's pretty much what everone uses. If you can mount the fan outside the case, you get, of course get more distance. I have a rad with a pusher/puller setup, and the pusher fan is 1-1/2 inches away, and the puller is about two inches, but the puller fan is mounted outside the case. Check out page 4 of the watercooling url in my sig. __________________ My Watercooling Stuff

06-20-2003, 12:46 PM	#4
JSimmons Cooling Savant Join Date: Apr 2003 Location: 4-sided room with an exit going east, and an exit going south Posts: 392	I don't think you'd notice much of a change by moving the fan away from a heat sink unless you had a duct that guaranteed the air was bing pulled over the fins of the sink. __________________ My Watercooling Stuff

06-20-2003, 03:26 PM	#6
Yo-DUH_87 Cooling Savant Join Date: Mar 2002 Location: Oregon, USA Posts: 230	Welcome to procooling, bty __________________ Signing out... Yo-DUH_87 If it works, fix it until it's broke! Then, after it's broke, add duct tape! Affordable webhosting!

06-20-2003, 04:45 PM	#7
hara Cooling Savant Join Date: Oct 2002 Location: Malta, Mediterranean Posts: 662	Welcome! First of all, in what direction is the fan blowing air? By spec, your heatsink should have the air sucked from it instead of blowing. If that's what going on then by moving the fan will in fact reduce the deadspot (since air sucked has a laminar flow) but don't ask me how much and if performance will vary. If your fan is pushing instead of pulling (like any other hs) than by moving the fan backward, performance could decrease since the airflow in front of the fan is turbulent. Heatsinks work well with turbulent flow but moving the fan back will not only shrink the deadspot but also reduce the airflow through the heatsink. What I suggest you experiment with is to get rid of the shroud and mount the fan the other way round (i.e. Blowing into). Some people reported better temps this way. __________________ - Every great HD crash day is the day before back-up day. - My Past System - "Better to reign in Hell than serve in Heaven." - Milton, Paradise Lost. - FMZ

06-20-2003, 10:46 AM	#3
Devil_H@ck Cooling Neophyte Join Date: Jun 2003 Location: Belgium Posts: 4	Hm, I'm using an Enermax fan with the large Alpha PAL P4 heatsink. Would there be a large difference in temperature if I move the fan 2 cm? I can move it more I think, I've got an AOpen HX08.

06-20-2003, 01:40 PM	#5
Devil_H@ck Cooling Neophyte Join Date: Jun 2003 Location: Belgium Posts: 4	Ok, nevermind then. Thanks anyway.

06-20-2003, 05:08 PM	#8
Devil_H@ck Cooling Neophyte Join Date: Jun 2003 Location: Belgium Posts: 4	Hm, I think I'm letting it blow, not sure though.

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