I need some help - Computer Case Design.

[RobbieThe1st]

Well, I need a bit of help, design wise.
I am going to get a new computer in a few months, obviously self-built, and I am going to build a case for it.
Here are the specs I am looking for:

• Maximum dimensions: 24" wide, 12" deep, 24" high.
  
• Material: Steel & clear plastic. Specifics are negotiable
• All I/O on the front. Power supply can be attached to the back, right or front.
• A minimum of four 5.25" CD slots, and two 3.5" floppy slots
• A removable plate, mounted somewhere on the front, with a minimum of 16 square inches. (This plate can be removed, switches and such added, then reinstalled. If I ruin it, or want a different design, I can make a new one)
• Easy to get to fan placement, such that I can put a filter on the ones facing inward. Positive pressure would be an advantage
• Motherboard can be either horizontally positioned(which may be a good idea, as heat can rise without being hindered by the various cards), or vertically.
• Motherboard spacing has to support a full-size ATX board
• Openings in the top are not really a good idea. I place stuff on top, and I don't like small things falling in, as it does in my current case

http://robbiethe1st.ktserv.com/images/compv4_20080730.png
This is what I sort of threw together, perhaps it is useful as a guide?

Note that I would like to see a design that is thermally effecient, that is, exaust fans near the top and such. I would like to use a minimum of fans, and 120MM fans for the ones I do need. I will be using a Zalman heat-pipe cooler, so leaving four inches or so above the top of that area of the motherboard is sort of needed.

I was planning on holding the thing together with small bolts and steel L's and or corners.

I admit I didn't provide quite as much detail as I could have; I can get anything you need.

I am a beginning machinist, and so will have access to a milling machine for drilling precise holes and cutting precise slots and openings.

Note that things are very much open to change, but I really don't want any responses like "Go to www.xxx.com and buy one of their already-made cases". Of course, "Go to www.xxx.com and take a look at feature Y" is perfectly fine.


I am tired now, and probably forgot something extremely important, so please post and I will see what I can do tomorrow when I get on. Thanks!


-RobbieThe1st


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[Ryudo Lee]

IMHO, the primary thing you want to look at is airflow.  You want to have space for a fan on the front and a fan on the back, as well as a vent on at least one side for intake to the processor.  You will probably have to get the motherboard first for that though.  Also, the inner structure should be minimalist at best, obviously for airflow and keeping temperature down.

[VSMIT]

The way you have it set up, according to your drawing, may not be the best of ideas.  While you can take air in from the back of the machine, you're going to have hot air spilling out in front of you.  I would consider switching the rear fan port and the PSU socket.  And adding a second fan port next to your existing intake port.

I've never seen a computer that has the I/O plate and the 5.25/3.5 drive slots on the same side.  Looks interesting, though.  Hope it does what you want to do with it.

[Azlan]

What the others have said is very true, airflow is key if you are looking to use fans and natural aspiration.  Conventional designs have Front fans bringing in air and rear fans exhausting it out causing a wind tunnel effect.  This is key in motherboard designs that rely on passive cooling for the Northbridge/Southbridge.  Airflow in case design is still an issue for even complete watercooling for CPU, GPU(s) and HD systems because of RAM and cooling for nothbridge/southbridge.

I would consider reworking your design with airflow considerations more heavily weighed.

[RobbieThe1st]

Well, I *was* planning on completely reworking the case anyway. I just need some tips and ideas on what shape would be best. Also, I have a nice aluminum motherboard tray, as shown in the design. I can either use that, or directly mount the motherboard(using standoffs of course) directly to the bottom of the case.

Airflow wise, I am thinking something like one 120MM fan at the front, somewhere near the bottom, and one at the back/top... or perhaps two near the bottom-front(perhaps on the sides near the front?), and just a vent at the back/top corner?


Note that with my current computer case, a full-sized tower, I have one fan at the top, one on the left side, in the center of the door, two on the back "above" the motherboard, and one in the PSU, which is at the top. All these fans are 92MM, and I am getting temperatures of around 40C on my various temperature sensors, even after working the computer hard - and the fans aren't spinning anywhere near full speed.
(Oh yea - the design had two fans in the front, which aren't turned on)

Because of that, I figure I can get by with two or three 120MM fans, IF I place them correctly. Also, the new computer is going to be cooler than this one, having a 65W AMD dual-core processor instead of a ~128W P4


-RobbieThe1st

[Jack McSlay]

given the specs you want, I see no way to do it without making something that's too huge for comfort. Why exactly do you need 4 5.25" inch slots and 2 3.5" slots? I never used more than one of each, so unledss you actually have plans for them I say you stick to only one of each

I think you can make something like 12"Width 12"Depth 10"Height if you put only one of each

[RobbieThe1st]

given the specs you want, I see no way to do it without making something that's too huge for comfort. Why exactly do you need 4 5.25" inch slots and 2 3.5" slots? I never used more than one of each, so unledss you actually have plans for them I say you stick to only one of each

I think you can make something like 12"Width 12"Depth 10"Height if you put only one of each

Well, my current case has five cd-rom slots, and two floppy slots. I am using four CD slots(2 for a Aerocool Gatewatch fan controller, one for a DVD-burner and one for my Creative Audigy 2 ZS control panel thing[it has various ports, and two volume control knobs - one for headphones, one for stereo-microphone in]) and two floppy slots(One for an actual 3.5" floppy, and one for an all-in-one flash memory reader).
I figure the best bet is to just stick a column of CDs on the left or right side, and be done with it. Yes, it adds an extra 6 inches to the width, but that isn't a big deal. As I said, I do have plenty of room, at least sideways, and I don't expect it to be portable.

But still, design ideas? like... should I put a fan(or two) at the top in the back facing outwards horizontally, or basically chop the last four or so inches at a 45-degree angle, so the fan is facing outwards and upwards? I am looking for little hints and tips and crazy ideas.


-RobbieThe1st

[Turnsky]

ideally you'd want your front fans to intake roughly where the hard drives are gonna sit, and the outlet roughly where the CPU sits, on most boards it's generally near the 'top' of the board.
for the sake of usefulness, i suggest going the extra distance and investing in thumbscrews, and making a cradle for the hard drives to sit in, you already have the idea of the Mobo sitting in a removable tray down right, so that's good, it just makes maintenance that much easier.

(ironically enough, what you'd want out of your case sounds like my old Lian-Li PC60 case, save one 5.25" bay, and one extra 3.5" bay.)

if you can i'd suggest nabbing a few cases and reworking the chassis for your needs, it might save you time and trouble, i'm fairly certain a lot of cases can be converted to what you need, especially any case that also has all metal structure.

[Jack McSlay]

if you have that much room, maybe you could put stuff on the top?

from what I see all the stuff woudn't suffer much from being put vertically, except for the DVD drive/cooler controller (tho i'd say, a rising DVD tray would look awesome

additionally, I suggest you use industrial-grade buttons and switches for power/reset etc. just because it would look awesome (they're useful for being to hard to be pushed accidentally tho)

[RobbieThe1st]

if you have that much room, maybe you could put stuff on the top?

from what I see all the stuff woudn't suffer much from being put vertically, except for the DVD drive/cooler controller (tho i'd say, a rising DVD tray would look awesome)

You mean facing upwards? Well, I think I could probably do it - the DVD drive couldn't be any worse than having it sideways. The controller wouldn't be hurt - all it is is a LCD screen and a bunch of circuitry - no moving parts. Still, I was hoping to have the top have nothing on it, and preferably few to no holes in it, as I tend to put stuff up top of it.

additionally, I suggest you use industrial-grade buttons and switches for power/reset etc. just because it would look awesome (they're useful for being to hard to be pushed accidentally tho)

That's a good idea - now, an ATX case needs momentary contact switches, but I could probably rig up some simple circuitry for using a standard non-momentary(I forget the proper term) switches. One idea would be a cool looking car-key type switch. You turn it to the on position, some lights and such turn on(there is the +5VSB line for power, even before the PSU is fully running), then just start the computer the way you would a car. I can probably rig up a simple circuit such that when, from running you flip it to off, it turns the comp off(Either interrupting the power to the PSU, or connecting the power switch lines together until it turns off, then opening the connection again.

Another idea is to have a relay with an external "button"(so you can manually turn it to the on position), press the button, it momentarially connects the lines, and through a "feedback" circuit(Actually, just having it connected to a +12V and ground lead would do this), turns on the coil, keeping it in the "on" position. Then, when the computer turns off, the power to the relay is turned off, allowing it to return to the "off" position. I would need to use some sort of simple transistor circuit to keep the computer from turning back off because the lines are still connected together(like you were holding the button in). It isn't quite as complex as it sounds, and would provide a satisfying *click* noise, both on start up, and on shutdown.

The best option would be to have a large-faced rotary switch, kind of like the key switch, but with a solonoid coil in there, such that when power to the coil is turned off, it goes to the off position(when the coil is on, it stays in the on position). Obviously, the coil wouldn't be strong enough to prevent you from forcing it off. The switch could also have a start position, but its not a requirement.


-RobbieThe1st

[Tapewolf]

Am I right in thinking that your design is a mostly-plastic case?  You might have RF problems unless it's shielded.

[VSMIT]

Just don't use a CRT screen. 

[Tapewolf]

Just don't use a CRT screen. 

Well, an unshielded case has two problems.  Firstly, it's liable to play havoc with other things, FM radio reception, for instance.  Induced noise in home recordings, in amplifiers and so forth.
Secondly, if you have a powerful transmitter nearby operating on the right frequency, outside sources may crash the PC.  It's rare, but not impossible.

[VSMIT]

Wow.  I knew about the first one (I play bass, and even a shielded computer wreaks havoc with amplifier noise), but the second one is a bit of a surprise.  I would think that if the transmitter was at the right frequency, it would shake the computer components apart before it shut down the computer.

[Tapewolf]

Wow.  I knew about the first one (I play bass, and even a shielded computer wreaks havoc with amplifier noise), but the second one is a bit of a surprise.  I would think that if the transmitter was at the right frequency, it would shake the computer components apart before it shut down the computer.

Offhand I don't remember hearing of it happening with a PC, but way back when, I saw a demo of someone crashing a BBC Micro using a CB radio.  (The BBC had a 6502 clocked at 2MHz).  Granted it may have been rigged, but if you can induce noise into the data bus, there's no reason you couldn't take Windows or Linux down the same way.

[Turnsky]

Am I right in thinking that your design is a mostly-plastic case?  You might have RF problems unless it's shielded.

Design and space wise, it might be worth mentioning that if Robbie grabs two ATX cases of roughly the same dimension height and depth wise, he might be able to quite easily marry the two via a few modifications. Putting the one where his mobo is going to sit on the bottom, with the IO and Card ports facing towards him as he wants, where the top one will have all his drives and such, removing the facing sides of each case and riveting the two case framerails together should be a no brainer, then all he's gotta do is grab a Dremel (or similar tool) and cut where he needs to cut.  This has the benefit of giving him -plenty- of room to work with, and most Modern tray drives can be operated at 90 degree angles these days anyway.

[RobbieThe1st]

Am I right in thinking that your design is a mostly-plastic case?  You might have RF problems unless it's shielded.

Yes, I was planning on making it mostly out of clear plastic. I don't quite know what problems I would have, however they can't be too bad, seeing as I see plenty of plastic cases around, and haven't heard much about them having more problems than aluminum or steel cases(well, aside from heat issues).

Just don't use a CRT screen. 

Fortunately I don't. I instead use a LCD with two (unshielded) HV(~600V) generators for the backlight. :

Well, an unshielded case has two problems.  Firstly, it's liable to play havoc with other things, FM radio reception, for instance.  Induced noise in home recordings, in amplifiers and so forth.
Secondly, if you have a powerful transmitter nearby operating on the right frequency, outside sources may crash the PC.  It's rare, but not impossible.

Hm... perhaps. Still, I don't listen to the radio, and don't have any wireless equipment, so I am probably pretty safe. I figure however that most problems would be experienced with low-end cheap motherboards using inadequate/missing HF filtering capacitors. 

I have noticed plenty of problems with Dell(low-end) and heard about Gateways having large problems as they were using capacitors and resistors with a ten-percent tolerance.

Still, I am hoping to build it such that it can be taken apart again, and pieces replaced as-needed. Then, if I really have to, I can replace several transparent panels with steel ones.

Design and space wise, it might be worth mentioning that if Robbie grabs two ATX cases of roughly the same dimension height and depth wise, he might be able to quite easily marry the two via a few modifications. Putting the one where his mobo is going to sit on the bottom, with the IO and Card ports facing towards him as he wants, where the top one will have all his drives and such, removing the facing sides of each case and riveting the two case framerails together should be a no brainer, then all he's gotta do is grab a Dremel (or similar tool) and cut where he needs to cut.  This has the benefit of giving him -plenty- of room to work with, and most Modern tray drives can be operated at 90 degree angles these days anyway.

That wouldn't be very hard, true. I could also take two, whack one in half, and use the second one to fill in the newly made gaps and such - I could then have both the drives and the motherboard horizontally aligned.

However, it wouldn't be transparent, which I am hoping for, and there is no way I am going to pay for two transparent cases, and put them together.


-RobbieThe1st

[Turnsky]

well, true enough, but since most cases have frames with metal sheeting on them, all you'd need is to remove the cladding from the frames, and eventually replace with clear plastic, that way you have all the proper structure of a case (not to mention all the mounting brackets), but it gives you the option to be able to route cables how you want within a cavernous space for better airflow.

Edit: and you'd have someplace to eventually 'ground' everything just incase.

[Tapewolf]

Yes, I was planning on making it mostly out of clear plastic. I don't quite know what problems I would have, however they can't be too bad, seeing as I see plenty of plastic cases around, and haven't heard much about them having more problems than aluminum or steel cases(well, aside from heat issues).

The Dell I'm typing this on has a mostly plastic case, but it does seem to have a Faraday cage in it as well.  What they used to do was coat the insides of the plastic with some kind of metallic paint to help shield it.  In fact, that may have been what Tomorrow's World was actually demonstrating.

Hm... perhaps. Still, I don't listen to the radio, and don't have any wireless equipment, so I am probably pretty safe. I figure however that most problems would be experienced with low-end cheap motherboards using inadequate/missing HF filtering capacitors. 

If you're in a semi-detached house, terrace or flat or something, you might screw with the neighbours, that's all.  If it's not going to be a problem for you or anyone else, go for it.

I have noticed plenty of problems with Dell(low-end) and heard about Gateways having large problems as they were using capacitors and resistors with a ten-percent tolerance.

Ewww.

[shadowterm]

An option, again concerning air flow, is to cut designs in the plastic sides and put metal with small perforations in, thus giving you a vent that combined with the shaped hole gives you a really cool design. Different perforation sizes are available, so you could make it as "Anti stuff getting in there" as you want. These can also be combined with a fan on the side instead of the front, but if the fan is cool looking you probably wouldn't want to do that. When putting in transparent plastic, keep in ind you can also fit those under designs cut into the existing material, which combined with lights would also look epic.

[RobbieThe1st]

An option, again concerning air flow, is to cut designs in the plastic sides and put metal with small perforations in, thus giving you a vent that combined with the shaped hole gives you a really cool design. Different perforation sizes are available, so you could make it as "Anti stuff getting in there" as you want. These can also be combined with a fan on the side instead of the front, but if the fan is cool looking you probably wouldn't want to do that. When putting in transparent plastic, keep in ind you can also fit those under designs cut into the existing material, which combined with lights would also look epic.

Hm... perhaps the best idea would be to have several fans on the front and left sides all pointing IN, providing positive pressure, and then an intricate design on the back side(dust wouldn't go in the back because the inside would be (a little bit) higher pressure than outside the case.


-RobbieThe1st