Making a CPU duct to draw outside air onto CPU!

[Web-Junkie]

Thinking about making a CPU duct so I can suck in cooler air from outside the case and blow it onto the CPU fan, not sure what to make it out of though! CPU is an AMD 2.8GHz Dual Core with stock cooler. Or should I be sucking hot air FROM the CPU and not BLOWING cooler air onto it?

Ideally I want to use an 80mm fan at the back of the case and make a right angle duct down to the 60mm fan on the CPU. I could do one from the side as I have 2 fans there too pulling air out so I could turn one around and it would be more or less straight but fancy the right angle approach as it would give more space for air flow.

Thought about square rubber tube (if that exists) or round rubber tube with thin walls so it can be stretched over a square 80mm fan and square 60mm fan, not sure if that can be 'bought' offshelf?

The reasoning behind this is my mobo/gfx card use passive cooling, no fans, and so radiates heat into the case. I have two 80mm fans in the side pulling air out and one 80mm fan at the back exhausting too and space for 1 more fan at the rear which is the one I want to use for the duct fan.

I also have a 120mm fan inside the case hung under the HDD bay blowing directly across the gfx card towards the rear of the case and another 120mm fan hung under the PSU with an inch gap blowing stright down onto the gfx card too, so all hot air is being blown towards the 80mm fans and exhausted.

But I think some of the hot air is getting sucked in by the CPU fan and making it spin faster and gets noisier, so that's the reason to make a CPU duct rather than fork out more money for different CPU cooler!

Maybe flawed logic but I like the idea of a duct as it won't be recycling hot air from inside the case!

Thoughts/criticisms/rofls/lmaos welcome Might go googling for info now!

[cmatt]

hmmmmmmmmmmmmmmm i understand the logic you want to use - infact i have see a few dells and compaq's use them. what i wouldnt do is put anything over the heat sink! The fan pulls air onto the heatsink to displace the warm air. If you cover this up - this one happen efficiently, if your using rubber tubing - then your nuts! :p

Theoretically - you get a 80/90mm case fan, and use that at full speed... (your case will have mountings for this anyway.... and duct from that onto the heatsink.... you will want to just mount the ducting 'on top' of the heatsink and not over it.... as that will defeat it's purpose!

You could use some largeish plastic bendy tubing come to think of it....

All those fans will interact with each other.

First priority is allways air in the front.

Whichever arrangement you use will have a negative effect, but I would go for this type of stuff to make it.
http://www.screwfix.com/app/sfd/cat/...01310&ts=05716

Overclockers is a good place to start:
http://www.overclockers.com/articles1256/

[Alien]

Originally Posted by Web-Junkie

Thinking about making a CPU duct so I can suck in cooler air from outside the case and blow it onto the CPU fan, not sure what to make it out of though! CPU is an AMD 2.8GHz Dual Core with stock cooler. Or should I be sucking hot air FROM the CPU and not BLOWING cooler air onto it?

It generally tends to work better feeding cool air onto a cooler, rather than trying to suck hot air from it.

Originally Posted by Web-Junkie

Ideally I want to use an 80mm fan at the back of the case and make a right angle duct down to the 60mm fan on the CPU. I could do one from the side as I have 2 fans there too pulling air out so I could turn one around and it would be more or less straight but fancy the right angle approach as it would give more space for air flow.

Thought about square rubber tube (if that exists) or round rubber tube with thin walls so it can be stretched over a square 80mm fan and square 60mm fan, not sure if that can be 'bought' offshelf?

Well, you've got multiple options for ducting, but I think your rubber idea is stretching things a bit.

To start with, you've got 2 types here:
Linkage
If you're only dealing with 80mm fixings, then the square ones look like a good choice, though you might have to do a bit of improvising somewhere along the line, as odds are that the straight & corner ducts won't add up to the exact length you need.

There's a few options here. The 80mm flexible tube kit looks like it'll cover most of your requirements, plus the various fan adapters would mean you could use it with different sized fans if you need.

Originally Posted by Web-Junkie

The reasoning behind this is my mobo/gfx card use passive cooling, no fans, and so radiates heat into the case. I have two 80mm fans in the side pulling air out and one 80mm fan at the back exhausting too and space for 1 more fan at the rear which is the one I want to use for the duct fan.

I also have a 120mm fan inside the case hung under the HDD bay blowing directly across the gfx card towards the rear of the case and another 120mm fan hung under the PSU with an inch gap blowing stright down onto the gfx card too, so all hot air is being blown towards the 80mm fans and exhausted.

Some pics might help.

Originally Posted by Web-Junkie

But I think some of the hot air is getting sucked in by the CPU fan and making it spin faster and gets noisier, so that's the reason to make a CPU duct rather than fork out more money for different CPU cooler!

I doubt the temperature would increase the speed of the fan, considering that the resistance of items that conduct electricity increases as they get hotter. Admittedly your average fan in your average PC isn't likely to encounter temperatures that would affect it by a noticeable amount.

Originally Posted by Web-Junkie

Maybe flawed logic but I like the idea of a duct as it won't be recycling hot air from inside the case!

That does make sense, and as I said, getting cool air into where it's needed is your best bet. Then, depending on the layout of your PC, you might be able to get some more improvement by doing something about how the warm air exits the system.

[Web-Junkie]

What about this:

http://www.kustompcs.co.uk/acatalog/info_2851.html

They also sell an 80mm to 60mm adaptor:

http://www.kustompcs.co.uk/acatalog/...ackets_27.html

So I could remove the 60mm fan from the heatsink, screw the adaptor to the duct then screw it onto the heatsink, then attach the other end to the 80mm fan and use the chimney on the outside.

That sound workable?

Posted at same time as you Alien

but I think your rubber idea is stretching things a bit.

Groan!! That's just so punny, sorry, funny

Can't do pics, no camera and I don't do 'mobile phones'!!

@data: found links similar at overclockers while googling, home made ducts though! Might try a home made one to test what happens!!

@cmatt: so only 1 fan is needed, no CPU fan, just a case fan blowing down a duct onto the heatsink? The sunbeam duct seems to screw directly onto the CPU heatsink?

The pre-made ones are a little unweildy, unless you shorten the pipe. They are also not the best flowing thing you could use.
Have a lokk at this article:
http://www.overclockers.com/tips1187/

Mine :
http://i104.photobucket.com/albums/m...al/CPUDuct.jpg

This is just a bad bad idea. Buy a decent cooler and a decent extractor for the rear with good ratings. The cpu cooler these days tend to cool other areas like passive cooled north bridge . I see no real valid reason to do this

[cmatt]

make your own ducting sir...

however just to point out... in custom pc - i saw a UUUUUBER cool (badoom tsh) heatsink - that was huge, ontop of it went 2 80mm case fans, i think it was zalman...

anyway - this one is very similar to what im trying to describe (and screwing said description up in the process):

http://www.overclockers.co.uk/showpr...=57&subcat=821

you could in theory keep the cpu fan....

http://www.overclockers.co.uk/produc...=821&mfrid=345 just listen to me and fit one of these

[cmatt]

Originally Posted by zinglebarb

http://www.overclockers.co.uk/produc...=821&mfrid=345 just listen to me and fit one of these

my friend got one of these: http://www.overclockers.co.uk/showpr...=57&subcat=821

no complaints from him

[Graham M]

I have a Dell Dimension here (2.26GHz) with the following configuration

[MovedGoalPosts]

Blowing cool air in over the hottest part of the PC might seem to make sense, but what then about all that warm air you've just created inside the case that's going to warm everything else up.

The only time I've seen ducting inside a case, is on some Dell server, and that's attached to an extract fan. The need for that becomes quite clear when the case gets filled with loads of disks and stuff so the air paths insdie the case can get too obstructed. Having said that my current Dell server has something like 10 different fans

It must be much better to concentrate on exhausting the warm air to outside.

My view, decent case with a front in, and rear out fan, plus the PSU extract fan, and a decent (not stock supplied) CPU cooler should do the job nicely.

---------- Post added at 10:53 ---------- Previous post was at 10:50 ----------

Originally Posted by zinglebarb

http://www.overclockers.co.uk/produc...=821&mfrid=345 just listen to me and fit one of these

Why the change from the Artic Cooler Freezer CPU fans you used to suggest

[altis]

I've always fancied a go at making a convection cooled PC. The plan is to cut a 6" hole in the top of the case and fit a good lenght (at least 2m) of extractor fan hose to it. This would run, as much as possible, straight up. I've never thought of connecting it to the outside but that would be good too. The idea is that the heat inside the pipe will cause the air to rise thus creating its own draught. With another bit of hose on the inlet we could have a balanced flue design!

Wherever the air comes from, try to make sure it's dust free so it doesn't all end up inside the case. Unfortunately, floors are particularly dusty and a bad place to have an air inlet.

[popper]

Originally Posted by Rob

Blowing cool air in over the hottest part of the PC might seem to make sense, but what then about all that warm air you've just created inside the case that's going to warm everything else up.

The only time I've seen ducting inside a case, is on some Dell server, and that's attached to an extract fan. The need for that becomes quite clear when the case gets filled with loads of disks and stuff so the air paths insdie the case can get too obstructed. Having said that my current Dell server has something like 10 different fans

It must be much better to concentrate on exhausting the warm air to outside.

My view, decent case with a front in, and rear out fan, plus the PSU extract fan, and a decent (not stock supplied) CPU cooler should do the job nicely.

---------- Post added at 10:53 ---------- Previous post was at 10:50 ----------



Why the change from the Artic Cooler Freezer CPU fans you used to suggest

as zing said its clear these style of coolers are far better at removing heat and more to the point directing it to the rear to be expelled, or above if your power supply has a large extraction fan fitting above the CPU slot.

a key idea most people forget is remembering to ballance both intake and outtake air pressure, thats a must for good cooling and distribution, remember also, front to back is the way todays standard cases are designed as far as air flow is concerned.

http://www.g4tv.com/screensavers/fea...e_Airflow.html

http://icrontic.com/articles/pc_airf..._cooling_guide

Originally Posted by Rob

Blowing cool air in over the hottest part of the PC might seem to make sense, but what then about all that warm air you've just created inside the case that's going to warm everything else up.

The only time I've seen ducting inside a case, is on some Dell server, and that's attached to an extract fan. The need for that becomes quite clear when the case gets filled with loads of disks and stuff so the air paths insdie the case can get too obstructed. Having said that my current Dell server has something like 10 different fans

It must be much better to concentrate on exhausting the warm air to outside.

My view, decent case with a front in, and rear out fan, plus the PSU extract fan, and a decent (not stock supplied) CPU cooler should do the job nicely.

---------- Post added at 10:53 ---------- Previous post was at 10:50 ----------



Why the change from the Artic Cooler Freezer CPU fans you used to suggest

well simply because my AC when I upped the vcore on my e6600 and hit over 2.8 ghz the fan would spin at its max and be to loud . The noctua doesnt speed up. For stock machines the AC is fine