HTPC case design

[Leuf]

I've been wanting to do this for oh, about two years. Have a dedicated pc for mp3/dvd/divx/video capture in my entertainment center. I finally have all the hardware for two machines and a kvm, so I'm good to go. However I have serious doubts that my full tower is going to fit in the entertainment center So I need to build a case for it. And seeing as my budget is $0, it's going to be made of plywood from the basement.

I thought some people might benefit from going through the design process I went through. I started by taking inventory on what had to go in the case and what I had available to use.

On the hardware side, it's got to hold all this:

ATX mb (kt7a)
1.2 gig tbird
4 cards (video,sound, nic, ide controller)
2x hdd (room for a third wanted)
dvd-rom
either sparkle 300w or enermax 350w psu

And for cooling I have on hand:
Alpha 8045
1x 120mm panaflo H1A
2x 92mm Innovative - 48 cfm
2x 80mm panaflo L1A
2x other noisy 80mm fans
bay cool 3 (from pc power and cooling)

I've never been able to find a dba rating on the 92mm fans, they came with the full tower. They're fairly loud at 12 volts but not too bad at 7. The bay cool saves me from having to build a hdd cage, and I've got it so may as well use it.

As design considerations, first as far as dimensions go the only definite is 17" width to match my sadly low end audio stuff. Depth is important, as the max depth I could fit is about 17", though I could move the whole thing further out from the wall in a pinch. Height is pretty unimportant, I'll be taking out the cd changer that is on its last legs which is 7.5", and I could move the vcr to another place or ditch the cassette deck if need be. I'd rather not have any fans in the front of the case, just for appearances and to help keep noise down. Most importantly, it has to be quiet. Lookswise, once it's in there you can only see the front and the first inch or so of the sides. And I don't want to have to be taking it out all the time to clean, I should be able to just stick it in there and forget about it. I won't be upgrading the box very much, ease of access is not a primary concern. The machine is not intended to run 24/7, only when I need to cap or play a movie, or I'm doing something with the primary machine that prevents me from using it as the mp3 player. But in a capping/encoding session it needs to be able to run full load for 12-24 hours.

To work out the layout I took the actual parts and started playing around with the actual parts on a 17" wide piece of plywood.

I started out with essentially a desktop type layout. There were a couple problems with this though. For one, the thickness of the 3/4" plywood sides only leaves 15.5" internal width to work with. This means that the mb and psu will essentially be right up against each other. The cpu socket on the kt7a is very close to the edge of the board, and the huge heatsink actually overhangs the board slightly. Plus the atx connector is right on the edge. I really didn't like that whole situation. Plus depth wise it was really pushing it, I couldn't do much better than about 21" or so.

I started playing around with having the psu partially over the pci slots, the bay cool sideways infront of the pci slots, and the dvd rom over the bay cool facing the front of course. It was pretty cramped over on that side of the case, and it would have meant the cards would be sharing irqs, but it was workable and I almost stopped there.

Then I thought well why not just turn the psu horizontal and put it up high enough to clear the cards. Then I was able to move the bay cool up in front of the psu, and the dvd over on the opposite side. This allows the depth to come way down, at the expense of being very high. And that is the configuration you see in the very not to scale attached drawing.

Now the question was how to make the thing buildable. I hit upon a pretty wacky idea. Make the case two open topped boxes, the top box sitting upsidedown on the bottom one. The mb is the only thing in the bottom box, everything else is in the top box. This makes building the case tremendously easy as I don't have to worry about access, and maintenance wise once the two halves are apart it should be very easy to work in. The only problem is all of the connections between the two halves. I can picture myself trying to hold the top up with one hand while fumbling around trying to plug in ide connectors. But, it's not too bad. Nothing in the bottom half needs a molex, so powerwise the only connector is the atx one, which is right at the edge of the board. And then all the ide connections. Then I thought I could put legs at the corners of the top that are as long as the height of the bottom box. This way you could lift up the top, rest the legs on the top of bottom box, and then have plenty of clearance to reach in to plug/unplug everything. Also, since the height of the whole thing is fairly massive, at least 10.75" I reckon, I could take advantage of the two boxes and make it appear to be two completely separate boxes, even though it would be open between them in the back half.

Am I completely bonkers?

For cooling, I am thinking that I will put 1 of the panaflo L1As in the baycool for hdd cooling and intake. The other L1A on the hs, I hope will be sufficient once I stop overclocking/overvolting the tbird, I can always switch to one of the other 80mms if need be. Then the 2 92mm fans for exhaust at the top of the case over the hs area, as well as the single 80 mm in the sparkle psu. For additional intakes I'll take the fan filter for the 120 mm fan, cut it in half and put a 60x120mm hole on each side of the bottom box, set back about 2 inches from the front. That way all of my intakes are filtered and still able to be cleaned out without having to completely pull out the box.

I have no experience with a wooden case, I'm hoping this is enough cooling. Hopefully I can run the 92 mm fans at 7 volts, I can always go to 12v if needed, or swap in the louder 2 fan enermax psu.

Any suggestions? I've already started working a little on it, I have the top and bottom pieces cut.

[gogo]

I had done something very similar before.
Some thing to consider.
The wood box that size will act like a speaker box, the fan and harddrive noise will seem to be very amplified.
With no metal sheilding your radio reception (AM mostly) will go to crap.

[Leuf]

I'm taking a wait and see approach as far as EMI goes. If it proves to be a problem then I'll have plenty of motivation to do something about it I'll do my best to make it easy to line the inside after the fact.

I hadn't thought much about the case acting as an amplifier, but that's going to be true of any case, isn't it? I've tried to keep the front of the box as free from holes as possible. The front will be a double thickness of 3/4 ply, with the frontmost piece hopefully being something more like MDF for looks if I can get a hold of some. The only holes are for the dvd, which will still be behind the front layer of wood, and the power/reset/leds. I've thought about putting baffles inside the side intakes. I'm not sure if lining the inside with foam to help cut down reflection will help at all.

Had a little bit of time to work on it today, but still didn't get too far. Rabbets done in the top and bottom pieces, and started on the side pieces for the bottom box. I'll snap a pic or two when I have something that starts to look like a box.

[gogo]

you can get pipe wrap insulation at most stores that carry weather seal stuff. There is this type that is about 3/16 thick and has foil on one side. It helped EMI. It also worked like a fill in a speaker box, made it sound like the box was bigger. the good thing is that it also made most of the noise come out the holes instead of the sides. on my proto type I had a 90mm on the side, a 80mm over the CPU and the fan from the PSU. The fans acted like very badly tuned ports.

Then again I've become very sensitive to noise.

Also remember that even if you were to 5V the fans, they would be very quit on the desk, but when you put the case into the cabinet with your A/V Equip, it'll be noticably louder. If you stack it on top of other equip., like an amp, the fan vibrations will probably tranfer and appear louder.

By no means am I trying to be negative or say don't do it (redundant?) Just relaying what I discovered. Strangely enough this is what got me into learning about speaker design.

I would sugest hooking up the fans and PSU. placing the other equip in the box so you have approx the same box relexes and putting the case where it will stay. Power it up and check the sound. Far easier to make adjustments now than later. It may save you from having to brak about glue.

I discovered that not having a side fan greatly redused noise levels. Because it was 17in wide the side fan ended up being 1/2 inch from a wall on the entertainment center. the sound just bounced around like crazy.

since all this I've moved to a smaller case and went woodless. I got an old Sony cd player online for $10, and cut the crap out of it.
I modified the front panel to hold a VU meter and a CF634 LCD. It doesn't have a CD or DVD any more, nor does it have incredible video. But it does play my mp3's of the server with no problems. It has a VIA933 so I just snaped on a Dragon Orb 3, took off the loud ass fan and put in a blue orb fan at 5V, just enough to get some air circulating. the only other fan is from the PSU and that's heat controlled.

After doing all this I thought I had a bad ground (getting feedback from the speakers when the PSU was plugged in and random resets) so I ran a ground wire from the PSU to the MB. It stlill got feed back and resets. Took it to the workbench and no problems. I tried replacing the power cord. no luck. Tor all the AV equip down and hooked it back up. still reset, but the noise was less so. I then realised the the Meter was on the same wall on the outside of the house. Plugged everything in to a line conditioner. No noise. and a lot better sound and picture. Just something else to consider I suppose. Though if youre on a budget a line conditioner is probably out of the question. They're pretty pricey.

[Leuf]

Don't worry, I'm not that easily discouraged. If I didn't want constructive feedback I'd have waited till it was done to post. I'm definitely dry fitting things first when possible so I can check the cooling and sound.

I've made pretty good progress on the bottom box. Sides are attached, and started on the partial top that is there to sell the idea that it's actually two separate boxes. For the motherboard mounting I usedbrass standoffs, but rather than attach them directly to the bottom of the case I made some 1/2"x1/2"x1/8" blocks, screwed the standoffs into those, attached them to the mb and then glued the blocks to the case. Why measure for 6 holes when you can just slap it on like that? It also buys me a little extra clearance incase I need to line the case later.

Speaking of which, that pipe wrap you're talking about is the stuff that comes in rolls, right? That could work, and it's pretty cheap. I also have some 3/4-1 inch foam I can use in strategic places for noise.

I'm fairly sensitive to noise as well, though as long as it's a steady noise I don't really mind. It can't be any louder than the full tower it's replacing, which I used to think was fairly quiet until I got a shuttle and did some work to quiet that down. And one of the benefits of this is I'll be able to pull one of the 2 hdds that's in the shuttle atm and put it in this box, so the main box will be even quieter.

If all I wanted was an mp3 box, I'd forget the 1.2 gig tbird and run the 486 that's been gathering dust

[gogo]

Oh yeah don't forget that wood and foam are much better heat insulators.

[Leuf]

Lots of progress, hopefully one more day of shop time and I can get it to where I can test. The bottom box is essentially done except the back plane. The top box, which is upside down in the pics, pretty much just needs its bottom.

[gogo]

ahhh, I see. It's going to be double stacked. cool.
don't remember if I mentioned it but I discovered that HD Designs Semi-Gloss black spraypaint is an excellent match fot black av equip. It holds up really well too.

[Leuf]

Well 4 hours in the shop yesterday and I got it together enough to be able to run it with the two halves just sitting next to each other on the work bench. With just the fans running it wasn't too loud. However I discovered one of the 92mm fans has a bad bearing. And it's pretty odd because it was highly noticeable but that fan had been in use in the tower and I hadn't heard it. And when I connected the hdd to power I found out why. Oh dear does that thing make a racket. It's an old drive, 8.4 gig maxtor. It's tempting to use the money I intended for an xp 2400+ for my main system on a new seagate, but I think I will have to make do with it. Or run the OS on the capture drive, which I'd rather not.

[Boli]

>>> If all I wanted was an mp3 box, I'd forget the 1.2 gig tbird and run the 486 that's been gathering dust

Incidentally... have you ever TRIED to play a MP3 on a 486? Sorry but I started on a 486 with Mp3s and I had to encode at 56kbs to get any sort of decent sound out. 128kbs (normal) didn't work at all.

Though it was funny that I was running it for weeks without realising that the CPU fan had broken off taking the heatsink with it... still worked and chugged along like a king, shame you can't do without a fan now... that would solve your problems with noise.