Case structure questions?

[Knothead]

I'm building a case from scratch. I have two computers here, plus an old (scavenged) case, and I'm comparing them for structure requirements...but I still have questions anyway...

1) Are Motherboards all about the same size?
2) do they all have a "universal" mounting bolt pattern?
3) Does a MoBo need to be mounted away from the case sides?
If so, why?
4) What part of the computer generates the most heat?
5) Are HDD's all about the same size? It seems CD's and floppy drives are.
6) Any reason not to use Plexiglass to mount the HDD and cd/floppy drives? (such as heat?)

Will prolly think of more as I go, but this much will get it started.

Thank you very much for your help! Todd

[FalcomPSX]

1) no, there are several standard sizes, the oldest ones you are likely to see being AT and baby AT. These require AT power supplies and AT cases. also, ATX, and MicroATX are also very common. and require ATX power supplies and ATX cases. Some AT boards can be mounted in a ATX case and will take an ATX power supply.

2) Somewhat, most full ATX boards have the same bolt pattern, usually consisting of 6 bolts. some larger boards use 9 bolts if they are wider. Micro ATX boards are usually bolted by 5 bolts, in a similar pattern to regular ATX boards.

3) Not sure what you mean exactly, but if you mean the brass standoff's, yes, you need to use those. If you bolt the board directly to the case, you can short out the board(metal on metal doesn't play nicely with electricity).

4) By far the CPU, does. Also, power supplies, if close to their max load can generate a decent amount of heat also newer video cards(Geforce(1-4), Radeon's, etc...) can get quite hot if not properly cooled(keep the pci slot directly below the agp slot free if possible). HD's can also generate a noticable amount of heat.

5) Yes, most are 3 1/2 inch(floppy drive size) drives except for some old Quantum Bigfoot drives(which are the size of a cdrom drive)

6) if you're building it yourself, you might whant to build a mount for a fan infront of your hdd's to help cool them. other then that, using plexiglass should be ok.

[crystaldragon]

"Any reason not to use Plexiglass to mount the HDD and cd/floppy drives? (such as heat?) "

The only thing I I can think of is the possible static electricity build-up. Not a good thing for electronics components or data!

You could get around that though by connecting a ground wire from one drive to the other with / at a mounting screw. and finally connecting it to ground. The casing on the power supply or the Green wire on the ac power cord should do the trick. That's the one that connects to the round lug on the plug.
That is one of the things about metal cases. Everything that should have or needs static protection is already connected through the metal itself.

[Knothead]

Thank you, Gentlemen, very helpful!

Falcom, please bear with me, VERY new to this, but why would I use

the oldest ones you are likely to see being AT and baby AT

? Are these the Standard type of MoBo? (In other words, do I HAVE to use an ATX board?) I'm planning on building a 'puter with (mostly) brand-new stuff...(Oh, and recommendations are GLEEFULLY accepted! )

Crystal, the minute you said STATIC, I thought about grounding...you may already know that this is not going to be a metal case. I suppose I'd have to attach a wire from each component, run it to a cental grounded screw, and then ground through the power line...sound about right?

Thanks, Todd

[Imanage]

For your project, you might want to get a really cheap ATX case(comes with mounting hardware) with a removable motherboard mounting tray. That way you can just worry about mounting the pan with some hardware clips. On most cases, the "cage" for the floppy/harddrive is removeable so you can mount that elsewhere. The holes are predrilled so why not use it. The main cage for 5 1/2 width stuff (CD-ROMS) is usually part of the sheetmetal side so you'll have to improvise there.

[amdkt7]

1) Are Motherboards all about the same size?
answer: no

2) do they all have a "universal" mounting bolt pattern?
answer: no, almost the same, but variations aplenty.

3) Does a MoBo need to be mounted away from the case sides?
If so, why?
answer: no, I would leave about 1/8 to 1/4 inch clearance tho.

4) What part of the computer generates the most heat?
answer: the cpu, next powersupply, then hard drives (most cases)

5) Are HDD's all about the same size? It seems CD's and floppy drives are.
answer: hd's are almost always 3.5", but height may vary. Floppies and cd's are pretty much always standard. Just give those hd's room for air circulation.

6) Any reason not to use Plexiglass to mount the HDD and cd/floppy drives? (such as heat?)
answer: should be ok, provided you get some air flow. I'd mount them (hd's) vertically (cables up) to allow natural air convection cooling.

Static electricity could be a problem during assembly, but after it's done it should be ok. Use a static strap, or ground yourself. Some drives do require the case to be grounded, but most do not. It would be best to use metal, but not required.

[FalcomPSX]

AT, and ATX...
all these refer to is the general layout of the motherboard. doesn't matter what you use, but they are quite different in layout and usually require a different power supply. AT power supplies are the ones with two motherboard power connectors labeled P8 and P9. ATX has a single connector, about the same width as both the AT connectors, but has two rows of pins.
looks kinda like this:

AT :
***** *****

ATX:
***********
***********

If you're using new parts, it will be either ATX or microATX, as AT parts haven't been commonly made for quite some time now.

[Knothead]

Thank you, guys, I really appreciate the help!

[Graham]

Wont add much, if the case is non conductive (e.g. wood) then putting the "solder side of the board to it wont matter. There are two considerations,

1 Heat, there is a small amount of heat dissipated from the back side of the board.

2. Not all the components/solder pads will be the same height, and they will all be proud of the board.

Thaking those two into account you should use some spacers, at least sufficient to raise the board enough to clear the solder joints, and to stop it flexing.

G

[amdkt7]

There is some need for air flow under the board as well, I'd use spacers the same size as standard holders.

How are you going to mount the cards? You might want to find an old case to use the back panel, cut it out and mount it in wood.

[Xaotic]

When mounting the drives, you can recess a strip of metal into the mounting rails making sure it contacts the drives. By doing this you can run a single wire(or use a similar procedure to route and conceal the ground fully) from the drive rails to ground the units. Form follows function and integrates esthetics as well.

[Knothead]

How are you going to mount the cards? You might want to find an old case to use the back panel, cut it out and mount it in wood

Yep! Although, who knows..I might get ambitious...I have a router and I ain't afraid to use it!!

When mounting the drives, you can recess a strip of metal into the mounting rails making sure it contacts the drives. By doing this you can run a single wire(or use a similar procedure to route and conceal the ground fully) from the drive rails to ground the units.

Excellent Idea! Yep! That's what I'm gonna do!

I think when it's time to begin the actual build, I'm gonna have a print=out of this thread, and Hi-Lite these ideas, that way, nothing gets lost. You guys are GREAT!!

[caddmannq]

Knot:
This is gonna be a lot of work, bud. I know you can do it, but here's my advice:

Don't skimp on the basic componants. Save up the extra dough & get modern stuff (DDR bus ATX mainboard w/ 4xAGP slot,and a good 300+ watt power supply.) Anything else is easy to upgrade later as you have the cash, but those two things will determine a lot about the layout of your case. You wont want to change them out later and find a lot of re-work to do on your finished machine.

As you design this, also keep in mind: heat rises, and it stratifies in the top of the case. Top-rear exhaust fan is highly recommend.

[Knothead]

Thanks, Cadd! That's exactly the kinda recommendation I was looking for!

On the revised design, the drawing doesn't show it, but there's about 1/2" of ventilation between the case and the (newly-added) top...that is, the top is mounted to the 4 stiles (corner posts) and makes the reveal on all 4 sides.

Try THAT with a metal case, LOL!

[Imanage]

This is a great project. You have people thinking inside the box, outside the box, and now a new term...on the sides of the box!

[Knothead]

on the sides of the box!

LOL!

Okay, I think the way to house the drives in front would be to construct acrylic boxes with holes in the sides...I spoke with a guy at Valley Plastics, who said that while acrylic plex IS technically a combustable material, it requires something like 200 degrees F. to ignite.

We've been talking about temps here, but does anybody know how hot it gets inside of a box? I mean, we all know if it were 200 degress all the time, it would likely melt stuff...but could there be peaks where heavy use runs it up, then maybe it cools back down? I hear a 1.4 GHz Athlon can get pretty toasty...

[amdkt7]

Between 86F to 120 F, though some surfaces may be higher, you should not be in contact with anything hotter then that.

A case that is cooled properly will only be about 15 to 20 F hotter than the room temps.

[Knothead]

AWRIGHT!!! Off I go then....Thanks, AMD!!!