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a duct without modifying the case... Tell me what you think (I'm a newbie)

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Petete

Registered
Joined
Nov 21, 2002
Hello All,

I'm new to this, and I've just had a (very good?) idea. I would like to know what you think about this (I'm sorry in advance if it's ridiculous or if it doesn't work).

I've been reading that Ducts make a lot improvements in cooling.
Since that means that you have to modify your case (and a lot of work), I've thought about another way to do it. Tell me if you think it can work (and also, where can you find the materials to do it ..:=)
OK...

What about if you put an adaptor to the intake fan (bottom front of the case - cool air) and you connect a flexible tube to it (you have a good presure there because the tube is smaller than the 80 fan) and you place the other end just in front of the heatsink fan? Then you'd have a lot of new fresh air directly over the CPU, and the other fan (outtake) would take all of the heat out of the case.

Another thing (maybe even better), would be to directly put it "over" the heatsink fan (with another adaptor), so in that case it would be 100% fresh air, all the time. Also, (correct me if I'm wrong) I think that in that case, the heatsink fan would carry twice as CFM to the heatsink. So you would have improvement because of the 100% cool air + improvement because of the increased CFM.

I think that the rest of the case doesn't really need to be cooled off, if the primary source of heat (the processor) is cooled this way, and the heat of the heatsink is pulled out by the outake fan.

I've thought even in making like a "little room" with some plastic in such a way that the hot air that goes out from the heatsink doesn't really go to the rest of the case, and it's pulled completely out by the outtake fan.

Well, maybe this is idiot, but I thought that it could be a good idea. Tell me what you think. And above all, if you think that is good, and you do it, please tell me what did you use to make it, because I would like to do it too, but I don't know where to find those things.... too bad :)

I hope it's not ridiculous and that it can help!

Petete

ps: if I've just discovered a new way of cooling, at least offer me a case with it, so I don't have to do it myself!! Just kidding ;-) .
 

Arkaine23

Captain Random Senior Evil
Joined
Nov 8, 2001
Ducting

Welcome to the forums!!!

This is a good idea and many people have pulled it off....

But there are some things to keep in mind- 1) like front case fans usually don't pull much air because of the way the grill and case front are designed. 2) Having a fan at both ends of a duct helps overcome static pressure but does not add the airflow of both fans together.
 
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flixotide

Member
Joined
Oct 29, 2002
Location
Denmark
Using the right tube, and building enough airpressure is the key for it to work. And as stated in the latter post, you might be able to pull it off.

Try and see if you can find some fairly even flex tube. Rubber tubing is good, as it is almost completely even on the inside and creates little surface resistance compared to standard flex tubing. Very little resistance is needed to slow the airflow from a 35-45 cfm fan..

For starters I would just settle with supplying your CPU Heatsink anf FAN with the air.. And try experimenting with different intake sources and fans.

Good luck, Flixotide
 

Valk

Member
Joined
Oct 31, 2002
I tried this just tonight actully... ended up taking the rest of the piping i baught and used it to force air in the back of my pc. the problem with this is simply room. if you are like me and have a full size motherboard, 2 hard drives and 17" case... running a tube from the front to the cpu mount is most unpleassant. to get it past my atx cables, hard drives and lower pci cards, i had to collapse the ducting to 2" from 3". I got fed up and just went back to my old duct. which was short and simple.
duct2.jpg

im lucky as my case has two case fan mounts RIGHT behind the cpu area of the board. I can see how you might have to rig ducting from the front bottom though. my last case had only the front mount for fans. It was the same kinda case i had here, but 15" tall. the power supply was mounted OVER the cpu fan and i needed some sollution to feed it with air. I ended up punching more holes in the bottom front, removing the mount for the fan entirely and glueing a thermal take smart case fan to it. behind it, i stuck some vinel ducting up through my case and tapering into my little amd case fan which i was force feeding 60 cfm into.

you are on the right track. dont be afraid to play with it. when i started a couple weeks ago, my temps were 45º idle, 56ºload. $64 for a thermal right heat sink and $10 for ducting material later (that was a good pizza btw), I amd running a cold 24º - 36º.

i did it by thinking exactly as you are now. oh, just as a bit of wisdom, dont be afraid to rape your case a little. its fun :D
 
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Petete

Registered
Joined
Nov 21, 2002
Great! Thanks for answering!

So, you think that it's better to orientate the tube just "near" the heatsink fan, and not to put it right "connected" to it with an adaptor? (because of "static pressure" (what's that???), or other things?)

One more question. How do you connect a tube (I thought I could use a washer machine hose) to the fan? what kind of adaptor do you use? or you do it by yourself?

thanks a lot again!

Petete
 

JasonKosi

Member
Those wiser can flog me if I'm wrong, but I believe that static pressure is any constant resistance against the flow of air.

A fan grill would create static pressure as is impedes airflow. A fandapter would also create static pressure as it creates a resistance to the flow of air as the channel narrows.

If you look at the manufacturer's specs for their fans (http://www.sunon.com, Sunon creates good quality, if uninspired fans), they will have a graph that shows the amount of air a fan can move given a certain amount of static pressure. The pressure is usually given in "millibars" or "inches of H20". Unless you have a highly sensitive barometer, this is simply to illustrate the relationship between flow rate and pressure.
 
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Petete

Registered
Joined
Nov 21, 2002
so you think that it would be better to put just a quite large tube (like 60 or 80mm) and make it go near the heatsink fan, or connect it "into" the heatsink fan? (if yes, wich one??)
You think that's better than having more pressure by narrowing the air conduct?

A second possibility, would be to remove the intake fan, and connect a tube from the heatsink fan (directly), to the place where the intake fan was, that way avoidying the static pressure. would that work, or it would be better to place the tube just near the heatsink fan, without "connecting" them?

Thanks for your help!

ps: one simple question. Is it better for the heatsink fan to be outtaking or intaking air?
 

Eclypsyr

Member
Joined
Aug 15, 2002
About the HS fan direction, I personal have air going onto the HS....and if you do duct air right to the HS/F, then have air blowing onto the heatsink, otherwise, the duct's only purpose would be disposing of warm air, rather than supplying the HS/F with cold air...
-Dae-


*edit* wording *edit*
 
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Petete

Registered
Joined
Nov 21, 2002
but do you think that is better to direct the air near the heatsink fan (like to create a cooler ambient), or directly "connect" the tube to the HSFAN so it just takes 100% cool air from the tube?
 

Arkaine23

Captain Random Senior Evil
Joined
Nov 8, 2001
Ducts

The static pressure you're up against is going to be caused by the walls of the duct and amplified by any curves the air must negotiate as it travels. Also the distance the air must travel is a factor. For these reasons more effective designs take air from a side panel vent and blow it directly at the HSF, or take it from the rear exhaust vent and blow it inward with a single bend in the ducting to aim it at the HSF.

Since you don't want to go through the trouble of modding your case, the latter option might easier to pull off, though your case will have less exhaust for hot air becasue you'd need to turn the rear fan into an intake. If you tried it that way, you'd want to make the front case fan into an exhaust fan and also build a small deflector around the outside of the PSU fan so that none of the hot exhaust from the power supply got pulled back in by your duct fan.

A simpler solution alltogether is just to remove the side panel and place a small house fan next to and blowing into your case.

tell us about your current case cooling... how many fans? their placement? do your temps drop when you take off the side panel?
 
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Petete

Registered
Joined
Nov 21, 2002
My actual case has 3 fans.

One intake in the front, one outtake in the rear up, and one slot blower (outtake).

As they are very noise (no name fans), I've ordered a Smart Fan II (thermaltake) and a 80mm normal fan to replace what I have.

My temps are quite high, but I think that I missplaced the heatsink or maybe the thermal pad (I thouched it (didn't do it on purpose) before I place it). I've ordered some Artic Silver 3 too, so I'll tell you when I get it and I put everything in place.

OK, my temps are:

31 Case Temp
41 CPU (when IDLE, WITH CPUIDLE)
52 or 53 (when IDLE, without CPUIDLE)
(the room is quite warm, too). But when it's cold, the Case Temp doesn't go down a lot (maybe to 27, or something).

I think that's very high (even the case... shouldn't be that high with 3 fans... The weird thing is that the temps go down only 2 degrees when I take the side panel off (29 and 38 when IDLE, with CPUIDLE).

Thanks for your help!

Petete
 

UnWishedLegacy

Member
Joined
Jul 21, 2002
Location
NorthEast England
Petete said:


OK, my temps are:

31 Case Temp
41 CPU (when IDLE, WITH CPUIDLE)
52 or 53 (when IDLE, without CPUIDLE)
(the room is quite warm, too). But when it's cold, the Case Temp doesn't go down a lot (maybe to 27, or something).

I'd say you had the same problem as me, what CPU are using BTW?

I had to do a clean install- but I had other problems too but I used this method to troubleshoot... I've suggested this toooooooo many times

Get an App called Wintop (use the search feature in the foums)- this tells you what proggies are using your system as well as how much power they are taking- I found that a file, Win32Lib.exe, was the source of my woes because it was chewing up over 86% of my processor (1.7G pentium4), as luck would have it... my local computer store was selling McAfee for 1/2 price- turns out it was infected with "Orifice" (sp?)- after cleaning it up- my CPU temps dropped over 10*c and my Case temps by around 5*c,

Original Temps= mid/high 50's CPU, early/mid 40's Case
Current Temps= low/mid 40's CPU, low/mid 30's Case

your case temps are fine- mine never goes over 36*c, but it wont hurt to re-seat your HSF again- even if you havnt smudged it it will be good practice if nothing else (and you can give it a good clean to- get rid of the dust thats bound to have accumulated.

Is your PC a store package (like Dell), and your worried about loosing your warrenty- be careful- apparently using stuff like Arctic Silver can void your warrenty (depending on manufacterer)- you might be best off sticking with the gunk that comes with your heat-sink, you only lose a couple of *C at most. <Anyone got clarification for that??>
 

UnWishedLegacy

Member
Joined
Jul 21, 2002
Location
NorthEast England
We will need to know that your running, what processor, windows/mac version and anything else that matters to your system. Do you have things like Bonzi Buddy or other things that run automaticly when you start the computer.. things like Bonzi chew up LOADS of CPU power, which can cause lots of heat.

Once you get Wintop you can see what %% of your core is used- whem in not doing ANYTHING but looking at my Wintop display, i get around 97% Idle, depending on the strength of your processor i would aim for things hanging around the high 80's/early 90's.

If you figure what your problem is- you will find that
A) Your temps will drop
B) Your games/applications will run faster/smoother/more stable
C) Peace on earth will ensue
D) We will all be sent a drink for our efforts...

OK, maybe not the 3rd one- but you definatly improve your temps and performance- and THAT is what counts :D

Sorry for double post
 
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Petete

Registered
Joined
Nov 21, 2002
First of all, I wanted to thank MikeTimbers for the picture. Does it work? Do you have any special tip for me to do it? where did you buy that tube? how many degrees did it drop? I'll try to do it, too.

Then.... let's see...
My Computer is:

Abit kx7-333 (non raid)
AMD Athlon XP 1700 (not OC)
256 DDR2700
2 Fan Case (1 + 1) + 1 Slot blower

My computer is already in 98 of cpuidle most of the time (you can see it by pressing CTRL+ALT+SUPR (maybe I'm wrong...), so I don't think that's the problem. But I'll try it out anyway.

thanks alot to all of you for your help.

bye, Diego.
 

Robin Hood

Member
Joined
Aug 8, 2002
Location
Nottingham
I have a Chieftech case set up in a similar manor to Valk with my AX7 drawing air through a closed duct to the rear two vents.

My case is 4 bays also - the bottom one is occupied by the DVD and the gap above is occupied by a 120 blowing out.

Additional case intake is via 2 80's in the base.
 
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Petete

Registered
Joined
Nov 21, 2002
I've just received a Thermaltake Smart Fan II and a reglar 80mm fan case. And some artic silver 3
I'll try them tonight and I'll let you know about the temps.

thanks!
 
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Petete

Registered
Joined
Nov 21, 2002
OK, i've installed the artic silver and now it's running colder.

It's running 4 degrees colder, but the most noticeble thing is that when not in idle, the cpu is colder, and it takes longer time to get hotter.

Just one question: Is the Thermaltake Smart Fan II very noisy, or mine is just deffective? (even in the lowest RPM, it makes a hum noise...)

thanks,
petete.