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Chassi Airflow and general fan questions

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March 24, 2010 7:21:10 PM

Okay, I've got a Chieftec Aegis case, pretty much identical to http://www.avadirect.com/product_details_parts.asp?PRID=11776, as far as fan positions goes it's almost the same, apart from that I (as far as I know) only have 2x92mm positions, both located on the side as seen in the picture.
I'm upgrading a little and I also bought some extra fans (3x120 mm, one for the top position and then 2 to create a push and pull type of thing for the H50 and 2x92mm) to try and create a nice airflow in the setup.
However I'm wondering how to attain it the best and since I have no position for a fan in the front (which is stupid) I'm kind of lost.
My idea is to set 2x120mm fans in the back around the H50 radiator and make them exhaust instead, since GPU exhaust is pointing to the backside I don't want to get that air back inside the case again. I'll put the last 120mm fan in the top position (roof of the chassi) also exhausting, since the hot air in the case will be rising anyhow and then the two 92mm fans in the side position, which by the HDDs in the chassi (in the front part) as intakes.

However I'm getting the feeling this might not be the ideal solution, any ideas on how to improve it?

Also since this is the first time Im installing any case fans, exactly how do you connect them? :ange: 
Mobo = M4A785D-M PRO (http://asus.com/product.aspx?P_ID=yCI8UenairUZJWET)
PSU = Silver Power SP200A2C 600w
120mm fans = http://www.fractal-design.com/?view=product&category=4&prod=18
92mm fans = 2150rpm http://www.scythe-eu.com/en/products/fans/gentle-typhoon-92-mm.html
Would there be a way to control these so that they do not go max all the time?

Input appreciated alot :) 

More about : chassi airflow general fan questions

a b ) Power supply
March 24, 2010 7:27:51 PM

This is a good guide to the basics of case airflow and is well worth the read if you're interested:

http://forums.techpowerup.com/showthread.php?t=42853

If you're adventurous and really want space for some fans in the front you mod your case to cut your own out ;)  Other than that you'll have to do the best with what you have. That guide should see you ok. Good luck!
March 24, 2010 7:56:25 PM

Ah thank you, nice guide - but it just increased my worry that top exhaust, back exhaust and then side intake isn't a super great idea.. perhaps it's even worse in this case, since the side without the fan holes is mesh(ed?), which is supposed to allow more air to enter easier in the case of a negative pressure setup I guess.

However, Im feeling like it might just make my side fans just blow out on the other side, which would be seriously "meh".
Any thoughts about either which fans should be which direction/how I could direct the side-fans' air-streams to the back of the case (how you create air ducts I guess) would be very helpful. ;) 
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a b ) Power supply
March 24, 2010 8:03:45 PM

I've always been unsure on side fans myself and tend not to use them. I favour the traditional front intake and rear/top exhaust method. The main reason I can think of to use a side fan would be to exhaust air from a hot spot such as your CPU or graphics cards. You sometimes see this on cases with a funnel that points onto such components to exhaust hot air away from them.

If it were me I would use rear, top and side fans all on exhaust. The negative pressure in the case will ensure that any warm air is expelled out of the case anyway. If you fancied, you could knock up a funnel-type device I mentioned to point to the hottest components to expel air straight off them.
March 24, 2010 8:09:40 PM

I agree with moody on turning all your fans into exhaust. Enough cool air will be pulled into the case naturally to allow those fans to get rid of the heat for you.

It's more important to pull the hot air out than to push in "cool" air.
March 24, 2010 8:25:14 PM

Hmm, super negative pressure, interesting idea but are you sure it'd work?
Maybe it would since the side is mesh and allows exterior air fairly easy access - at least until I got an idea for how to drill a circular hole in the front..
Oh and, what is this funnel device, is it like a tube or is somewhat open?
Also would a fan in the floor of the case work, does it take in enough air to be worthwhile?

And finally, exactly how do you connect the fans and to what? I've never done that before so.. yeah, I'll probably figure it out but any general tips would be great.
a b ) Power supply
March 24, 2010 8:47:38 PM

You can drill a circular hole in the front of your case using a holesaw. They come in various sizes so just go as close as you can to the size you want. You can then buy a fan grill or something similar just to protect you rfan and ensure nothing gets in the way while its spinning.

The funnel device is roughly something along these lines:

http://i.neoseeker.com/neo_image/146682/article/centuri...

Just something that will direct airflow a bit better than a standard fan by itself.

A fan on the floor probably wouldn't give intake as much air as it would on the front and you have to be careful with dust when you use fans on the bottom of the case since obviously any dust will always settle on the floor of whatever your PC is stood on.

Some fans come with a molex connector which will connect straight to a spare molex plug from your PSU. Others have a connector which needs to be connected to the chassis or system fan header on the motherboard. The trouble with most boards is that they only accomodate for one system fan.

The solution is to 'adapt' a spare molex connector to power your fans. Some people also call it splicing. Basically you cut the connector of a molex plug from your PSU so you have just the wires. You also cut your connector from your fan. Since all you need to run a fan is a +12V and 0V supply you connect the appropiate ends of each cable together. However you have to bear in mind that the colours are different for a molex and 3-pin fan connector:

Molex:

Yellow: +12V
Red: +5V
Black: 0V

3-Pin Fan:

Red: +12V
Yellow: Speed control
Black: 0V

So you connect:

Yellow from the molex end to the red of the fan end.
Black from the molex end to the black of the fan end.

Most molex connectors have two blacks, either will do. Just tape the spare wires up so they don't touch anything.

You have a couple of options for connecting the two ends of the cable. A crimped connection is more electrically sound. You simply strip a length of insulation from your wires and twist the ends you wish to join together. You then insert these into a crimp and clamp down to close the crimp and terminate the connection. You can use a crimping tool to do this or if you don't have one a pair of pliers will probably do the trick. It's a good idea to tape up the crimp also to ensure that everything stays where it should.

You should be able to pick up a pack of crimps from any electrical store. Go for the smallest size and just explain what you need to do. The assisstant etc. should be able to help you if they're worth their job title ;) 
March 24, 2010 10:46:36 PM

Yeah, my fans are all (:( ) 3-pin which my mobo doesn't support, Im thinking about a http://www.fractal-design.com/?view=product&category=5&prod=23 which uses one PCI slot (which I have two of) and then splits it into a multitude of mixed 3/4pins, which fits me well.

I also looked at hole-saws, might do that eventually :)  it seems hard finding a 120mm.
March 25, 2010 1:03:16 AM

I got a Scythe Master Ace fan controller - fits into a 5 1/4" bay and looks cool - RPM for each of up to four fans and temps for four sensors they give you to put wherever you want. Runs off one molex connector. Uses the 3 pin plug to attach to the fan (there are three pins for each fan which stick out of the back of the plate....
!