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Fan position in a custom built HTPC case?

balidey

Distinguished Member
Hello,
First I'll introduce myself and my reason for the odd question, I'm Steve and I'm a Design Engineer by trade.
My previous PC experience is that I have built my own PC's from parts handed down from my mate's upgrades. So my PC has always been quite good quality items, just about 2 or more years old. But it does the job for what I wanted it to do.

Until now that is.

I have recently bought a nice(ish) Sony HDTV and I want to build an HTPC. But the way I work is that I love to do things on a really strict budget. So rather than buy a case, I am building one. From scratch. Designing and making things is what I do for a living, and I get a real satisfaction from these little projets.

The internal components will all be bought or borrowed from other machines, but the case will be made by me from an alloy frame with carbon fibre panelling. The reasons for this are 1) I have access to the alloy and carbon and I can use them well and 2) it should look cool.

The other reason for a custom case is that I have a really limited amount of space in my TV stand, and most of the HTPC cases off the shelf were way too big, so I have decided to make a custom sized one. And with a carbon front I should be able to make it look cool and sleek.

I have a couple of old PC cases that I can rob drive bays etc from. But the thing that I am really stuck on is fan placement as its not something I have had to consider before (even though I have been involved in whole vehicle aerodynamic studies, I know a lot about the process, just not how best to do it inside a PC case).

My TV stand has a half height front door to it (one shelf is open, one is closed by the door), so it will not get much air circulation, so I am thinking I need more fans. But the fact it has a door means that noise should be kept to a minimum. I am also considering using noise absorbing material in the case panels if needed.

If the front door on the TV stand is a major problem to cooling then I can move my AV stuff around and put the HTPC in the TV shelf without the door, but I don't want to do that if I don't need to, ie not get enough cooling.

Using a CAD program called SolidWorks I have modelled the case so far. Pic below.

FANS.jpg


DVD all in one drive will be central and high up. Below it will be one (maybe 2) HDD. Mobo will be back left, PSU back right. Exhaust fan I have put central in rear.

Front fans I have two options, either blowing across directly onto the DVD and HDD or I could mount then in the floor in a similar location, but blowing upwards. So I am then sucking in air from the sides (near the front) and exhausting at the rear.

Would a pair of 80mm's be OK, or 120mm's? Any advantage of positions on the side or floor?

I was thinking about fitting some internal air guides, to direct some airflow towards the CPU and the mobo. Is that worth considering? A nice little carbon fibre air scoop perhaps? Is it even necesary?

The CAD model is still just that, so I can move as many things round as I need to. Altough the alloy frame will probably be started this weekend as I have the bits ready to go. Then I will start putting in the drive bays so I can work out the front panel. Then base and side panels.

So, any comments on fan numbers and positions so far?

Size will be approx 420mm x 420mm x 130mm.
 

jameson_uk

Well-known Member
So, any comments on fan numbers and positions so far?
too many :cool:

My HTPC is sat in a small shelf under the TV and there really is not much room for air to get into it. I have 2 undervolted 120mm fans as exhausts (only because there are 2 x 120mm mounts, the second fan actually makes little difference to temperature) and an 80mm fan on the CPU and whatever is built into my PSU.

With a HTPC silence is quite important but there is a balance between heat removal and noise. A lot of this comes down to what components you are using and more so what processor. If you are running an old P4 then you probably need loads of cooling where as a newer processor will require a lot less.

The major question is whether you want a cool system or a quiet one. The two (to some extent) are mutually exclusive.

If you have the chance to design your case then make sure you go for 120mm fans. These can push a lot more air than 80mm fans producing less noise. I believe you only actually need a fan on the CPU cooler, and exhaust and one on the PSU.

If you have a PSU with a 120mm+ fan then I would try and arrange it so that the PSU is also acting as an exhuast.

One thing to consider here is the CPU heatsink. This probably makes the biggest difference to cooling. My main machine is running an Intel E6600 passively :D I use a Thermalright HR01 connected up to the 120mm exhuast and it runs fine.
 

deksawyer

Active Member
Hi, and welcome to the forum!

I agree with my friend above that you have too many fans in your plan.

Over the years I've used a few HTPC cases and each time I change I learn something new and end up with something better.

My latest case, an ill fated Omaura TF8, is superb. It comes with 2 rear/side 80mmx15mm fans and 2 front/side 60mm fans (which were the first things to be removed!). It's as quiet and cool as you'd ever want.

I have cool running components, with the exception of the North Bridge, which can run up to 70 odd degrees C I'm told. My CPU is curently sitting at 24 degrees C and the NB is 54 C. The fact that the exhaust fans are right next to the CPU is a very important factor and you should rethink your design around that idea.

120mm fans aren't nescessary in my opinion and if you want your case to be slim, then they're a no-no. Intake fans aren't needed either as long as there's plenty intake area; ie holes above the CPU.

Here's an early pic of the case internals;

original.jpg


More pics here; http://www.avforums.com/forums/home...ura-tf8-hi-def-slim-media-player-build-2.html

Keep us posted as this looks like and interesting project...

D.
 

spyder viewer

Distinguished Member
Look at the design of commercially produced cases.
Does carbon fibre conduct heat well?
Use fans that you can control the speed of.
Use a low energy processor.

Could you design one for me?;)
 
E

eucalyptus9000

Guest
Have a look at www.quietpc.co.uk - they have an interesting selection of quiet fans and the like. Look at getting a fan controler / temp monitor installed (at least until you work out where the hot spots are). I appreciate that you are trying to do this on a strict budget but a cool, quiet system does not really come from the throw-outs pile. Things like the heat-pipe coolers and oversized heatsinks are fantastic. I would consider making your case from big slabs of aluminum as this will REALLY help the conduction. If you want to see some carbon then maybe consider some overlay inserts?

120mm fans at a reduced speed will be your best bet - the speed controllers are really cheap.

I have a small form factor case (Silverstone SGO1) with 2xhdd, 1xoptical, micro atx mobo and an intel e6300 ustilising a large fanless Asaka copper heatsink which just rely's on the case fans (only 60mm x 2) and the psu to shift the air. No problems with over-heating, but I would prefer to get some lower speed oversized fans fitted with a fanless psu.

A further point to consider is I have recently seen an externally mounted psu that is housed in an alloy case in order to help remove a major heat source from the htpc case.

Good luck.
 

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