Old Thrashbarg wrote:

then don't use the plastic standoffs. An AT board can be attached with metal standoffs and screws just the same as an ATX board.

...However, keep in mind that no ATX case is going to be perfect... AT boards are 8 slot, ATX cases only have 7, so you'll lose use of the top expansion slot.

Possible caution: you may need to electrically isolate those standoffs. Note that you can get nylon standoffs in the same sizes as the metal ones. Try Digikey and Mouser in North America. Or just your scrap bin; I've got a few from something. Or just thread screws into drilled blocks of plastic/wood - experiment with what you have on hand.

You'll have to do more-interesting tin-work to make everything line up at the back.

Don't get too intimidated by that idea. If it's a first project, take your time and figure on making some mistakes to learn things. But most of the metal in the new cases is very thin stuff.

Remind yourself that Hams used to build nice radio chassis with an egg-beater hand-drill, a coping saw, and a couple of files. And they used much thicker metal.

Also for the back - in places where you need coverage rather than strength, you can use very thin sheet like old Macs used for shielding. You can cut that with good scissors.

Also you can get aluminum cheap by the foot from builder-supplies - they sell it in rolls for soffits. Usually painted white or brown on one side, natural on the other. You cut this by scoring it with a utility knife then bending it to break. Drill it by sandwiching it between two pieces of scrap wood to stop deformation.

Etc..

Disclaimer - I trained for aircraft aeons ago, and have worked as a cabinetmaker and carpenter. This is what I'm good at, rather than the electronic and the digital. So I've got a different viewpoint. This may not be an adventure you're interested in.

But a lot of times people just let themselves get too intimidated. My advice is experiment -- make your first bends and holes on scrap pieces to get the hang of it. When people start this sort of thing they just get too wound up about getting things perfect on the first go, instead of letting themselves learn, so they never start.

All you need to do here is match what's happening mechanically and electrically in an AT case.

Also note that the cases are often held together by rivets. You can drill rivets out. Use an oversize drill to go gently down to mere decapitation of the rivet on the near side. Push it out the other. Then you can use a nut and bolt, or pop-rivet, for reassembly. Add that option to your mental tool-set when you're looking at what you want to change.

Er, sorry. The ideas just start coming once someone asks a question like this. For me it's like I'm a dog and you've thrown a ball. 😀

EDIT (already):

The big deal will be getting good alignment between the back plate and the mother-board mounting-plate.

If it's not good, then when you screw down the ISA cards, you'll pull them out of their slots a little or a lot. Probably you've already run into this with warped cheap cases once.

I'd say reference the back plate first, and adjust the motherboard plane by adding washers to the standoffs if necessary. If more than a couple of washers, use different standoffs.

EDIT (again, yikes)

You can probably find dimensioned drawings online for AT cases. Treat these with caution, rather than definitive. It'd be better to modify an ATX case using dimensions from a known good AT case alongside. If you don't have that physical reference, then proceed cautiously. Consider drawings as Good Advice rather than Final Word and keep your eyes open. Do lots of test fits. I'm going to try to shut up now.

3rd EDIT

When I say washers above, I mean the little red fiber ones that you've probably collected a number of already. Don't use metal washers against the back of your motherboard to adjust that plane.

Great contribution!

pewpewpew wrote:

Possible caution: you may need to electrically isolate those standoffs. Note that you can get nylon standoffs in the same sizes […]
Show full quote

Old Thrashbarg wrote:

then don't use the plastic standoffs. An AT board can be attached with metal standoffs and screws just the same as an ATX board.

...However, keep in mind that no ATX case is going to be perfect... AT boards are 8 slot, ATX cases only have 7, so you'll lose use of the top expansion slot.

Possible caution: you may need to electrically isolate those standoffs. Note that you can get nylon standoffs in the same sizes as the metal ones. Try Digikey and Mouser in North America. Or just your scrap bin; I've got a few from something. Or just thread screws into drilled blocks of plastic/wood - experiment with what you have on hand.

You'll have to do more-interesting tin-work to make everything line up at the back.

Don't get too intimidated by that idea. If it's a first project, take your time and figure on making some mistakes to learn things. But most of the metal in the new cases is very thin stuff.

Remind yourself that Hams used to build nice radio chassis with an egg-beater hand-drill, a coping saw, and a couple of files. And they used much thicker metal.

Also for the back - in places where you need coverage rather than strength, you can use very thin sheet like old Macs used for shielding. You can cut that with good scissors.

Also you can get aluminum cheap by the foot from builder-supplies - they sell it in rolls for soffits. Usually painted white or brown on one side, natural on the other. You cut this by scoring it with a utility knife then bending it to break. Drill it by sandwiching it between two pieces of scrap wood to stop deformation.

Etc..

Disclaimer - I trained for aircraft aeons ago, and have worked as a cabinetmaker and carpenter. This is what I'm good at, rather than the electronic and the digital. So I've got a different viewpoint. This may not be an adventure you're interested in.

But a lot of times people just let themselves get too intimidated. My advice is experiment -- make your first bends and holes on scrap pieces to get the hang of it. When people start this sort of thing they just get too wound up about getting things perfect on the first go, instead of letting themselves learn, so they never start.

All you need to do here is match what's happening mechanically and electrically in an AT case.

Also note that the cases are often held together by rivets. You can drill rivets out. Use an oversize drill to go gently down to mere decapitation of the rivet on the near side. Push it out the other. Then you can use a nut and bolt, or pop-rivet, for reassembly. Add that option to your mental tool-set when you're looking at what you want to change.

Er, sorry. The ideas just start coming once someone asks a question like this. For me it's like I'm a dog and you've thrown a ball. 😀

EDIT (already):

The big deal will be getting good alignment between the back plate and the mother-board mounting-plate.

If it's not good, then when you screw down the ISA cards, you'll pull them out of their slots a little or a lot. Probably you've already run into this with warped cheap cases once.

I'd say reference the back plate first, and adjust the motherboard plane by adding washers to the standoffs if necessary. If more than a couple of washers, use different standoffs.

EDIT (again, yikes)

You can probably find dimensioned drawings online for AT cases. Treat these with caution, rather than definitive. It'd be better to modify an ATX case using dimensions from a known good AT case alongside. If you don't have that physical reference, then proceed cautiously. Consider drawings as Good Advice rather than Final Word and keep your eyes open. Do lots of test fits. I'm going to try to shut up now.

3rd EDIT

When I say washers above, I mean the little red fiber ones that you've probably collected a number of already. Don't use metal washers against the back of your motherboard to adjust that plane.

This post makes me wish I had a set of metric taps 😁.

I'm decent enough with my hands, I had never really thought to mod a case to allow for a new motherboard 🤣 .

As for height of the standoffs, I'm pretty sure that measurement stays the same for AT and ATX (I.E. just use what the case came with height wise). The backplate won't line up, but one has to make a custom one or leave that open any ways. Some of the locations are also the same at least in my experience, although many are not.

SavantStrike wrote:

This post makes me wish I had a set of metric taps 😁.
...
The backplate won't line up, but one has to make a custom one or leave that open any ways

- What do you need to tap that can't be done with a hole and nut?

- Probably shouldn't leave it entirely open; you want shielding. But that's a good point - other than the screws at the cards, the rest of the connections sticking out the back of an ATX are hanging in space; they're not using the backplate for support. So it simplifies things. The back plate there is just a curtain. You can use the thin, scissors-cutable, shielding from old macs to be the shielding around those. Or aluminum and proper tin snips. Or ______.

There are so many ways to skin cats... This is just an exercise of staring at what the case has to be, staring at your parts pile, and letting your creativity think about it while you're doing other things. You'll come up with ideas the more you play.

Jakodemus wrote:

Does anyone know is there a modern atx-case where you can mount an full size AT motherboard? I read that some Coolermaster cases should have AT-mountingholes.

Wouldn't virtually all (non-oem) ATX cases come with the AT mounting holes? Iirc I've seen them a lot in the older ATX cases.

pewpewpew wrote:

- What do you need to tap that can't be done with a hole and nut? […]
Show full quote

SavantStrike wrote:

This post makes me wish I had a set of metric taps 😁.
...
The backplate won't line up, but one has to make a custom one or leave that open any ways

- What do you need to tap that can't be done with a hole and nut?

- Probably shouldn't leave it entirely open; you want shielding. But that's a good point - other than the screws at the cards, the rest of the connections sticking out the back of an ATX are hanging in space; they're not using the backplate for support. So it simplifies things. The back plate there is just a curtain. You can use the thin, scissors-cutable, shielding from old macs to be the shielding around those. Or aluminum and proper tin snips. Or ______.

There are so many ways to skin cats... This is just an exercise of staring at what the case has to be, staring at your parts pile, and letting your creativity think about it while you're doing other things. You'll come up with ideas the more you play.

I would worry that the nuts might loosen over time if one is in the habit of removing the motherboard frequently. That said, it wouldn't be a big deal to tighten them again.

As for EMI, I've found systems are pretty tolerant. I've had a fair number of windowed systems and that's an open side panel with plexiglass. One might as well have a huge gaping hole in the case as far as interference is concerned. I've never had a problem with the computer malfunctioning, nor with nearby devices picking up interference, including wireless devices.

Tetrium wrote:

Wouldn't virtually all (non-oem) ATX cases come with the AT mounting holes? Iirc I've seen them a lot in the older ATX cases.

Those older and "first generation" ATX cases (those that were accompanying the new ATX standard boards), while AT standard cases were being phased out, do have them.

Some were "kind enough" to place AT-specification mounting holes in some later ATX cases. (My Pentiium 4 1.7 GHz system casing has mounting holes for AT boards - they are labelled by etched words on the base.)

Since many are interested in this AT mobo in ATX casing thingy, I'll try experimenting with one of my socket 7 boards in the P4's ATX case and post some pictures with results soon.

SavantStrike wrote:

I would worry that the nuts might loosen over time if one is in the habit of removing the motherboard frequently. That said, it wouldn't be a big deal to tighten them again.

As for EMI, I've found systems are pretty tolerant. I've had a fair number of windowed systems and that's an open side panel with plexiglass. One might as well have a huge gaping hole in the case as far as interference is concerned. I've never had a problem with the computer malfunctioning, nor with nearby devices picking up interference, including wireless devices.

I see.

For the example of a mounting a motherboard standoff, use just a bit of silicone sealer as a poor-man's Loctite. Loctite itself is overkill, and most of the items sold as lockwashers in this size aren't much good.

For EMI I agree. The only interference I've ever noticed is audio cables, or between amp and CRT. I was thinking more how boards tend to have generous contacts around the plug sockets to touch the case. But this is likely redundant grounding - people do acrylic and cardboard cases, after all.

You know, looking at a no-name ATX case I've got on the bench right now, the panel for the plug sockets is a sub-unit that detaches with two screws -- probably for quick alteration to fit different spec'd boards. A case like this one could be converted to 7 card AT use with very little fuss.

Probably the only fiddly bit is mounting the different style power switch. Where that's not a near fit, one will have to alter the usually thicker front metal. And some of the 120vac switches are snap-fit -- these require an accurate hole.

Otherwise things do look close. Even two opposite-corner PSU screw holes look like a possible match.

Another thing to remember about AT cases is the DIN keyboard socket and D-SUB cutouts for attaching multi-io cables. ATX cases won't have these and you need to use an ISA slot to mount the multi-io ports, and will need a custom backpanel to cover the keyboard port.

YMMV - 3 of my 4 ATX cases have multiple D-SUB cutouts. 4th has only one large cutout.

megatron-uk wrote:

Another thing to remember about AT cases is the DIN keyboard socket and D-SUB cutouts for attaching multi-io cables. ATX cases won't have these and you need to use an ISA slot to mount the multi-io ports, and will need a custom backpanel to cover the keyboard port.

There is a lot of room aside from the DIN keyboard slot. Enough space you could easily put a PS2 mouse port and a in there, as well as a pair of usb ports. Probably even a pair of serial ports.

EDIT: I'm still not sure much work needs to be done regaring the height at which the motherboard sits. It's been my experience that the slot spacing and the height of the board is the same for AT and ATX, with the exception being the holes are in a different location for AT, and AT has 8 slots.

megatron-uk wrote:

Another thing to remember about AT cases is the DIN keyboard socket and D-SUB cutouts for attaching multi-io cables. ATX cases won't have these and you need to use an ISA slot to mount the multi-io ports, and will need a custom backpanel to cover the keyboard port.

Some very early ATX cases had these actually.

Btw, I never realized ATX used only 7 slots while AT uses 8. So much for putting an AGP AT board into an ATX case 😵

Tetrium wrote:

megatron-uk wrote:

Another thing to remember about AT cases is the DIN keyboard socket and D-SUB cutouts for attaching multi-io cables. ATX cases won't have these and you need to use an ISA slot to mount the multi-io ports, and will need a custom backpanel to cover the keyboard port.

Some very early ATX cases had these actually.

Btw, I never realized ATX used only 7 slots while AT uses 8. So much for putting an AGP AT board into an ATX case 😵

Yeah, that's unfortunate isn't it?

No love for SS7 baby at boards. A lot of them that I've seen had 4 PCI slots and 3 (one shared) ISA slots, with the agp slot as the 8th. The Asus P2B-99B works though 😀. Slot 1 and baby AT are a tasty combination I suppose, although also a fire risk...

A lot of the later BabyAT boards (i.e, most Socket7 boards, and I think all Super7 and Slot1 boards) were actually designed to work in either AT or ATX cases. They fit within the seven slot ATX limitation, often had both AT and ATX power connectors, and even the mounting holes mostly matched up with the ATX mounting layout (except for a couple along the top edge of the board). There were even a fair number of PCI 486 boards designed for seven slot cases... the HOT-433 pictured in this thread being a good example.

Old Thrashbarg wrote:

A lot of the later BabyAT boards (i.e, most Socket7 boards, and I think all Super7 and Slot1 boards) were actually designed to work in either AT or ATX cases. They fit within the seven slot ATX limitation, often had both AT and ATX power connectors, and even the mounting holes mostly matched up with the ATX mounting layout (except for a couple along the top edge of the board). There were even a fair number of PCI 486 boards designed for seven slot cases... the HOT-433 pictured in this thread being a good example.

Thanks for pointing this out.
In this case it shouldn't be too much of an issue. Even if a board has 1 slot more, it's probably not the AGP slot but a PCI (usually) and 1 slot can be missed if it's an 8th (and thus, an extra) slot anyway 😀

Alright, here's my recent experimentation with my ATX case with AT-compatible screw holes and an AT motherboard :

My ATX casing which originally came with my P4 1.7Ghz :

The ATX casing has seen multitudes of other mobos, and hence an assortment of stickers remaining on it.

Inner view :

Close-up view of the screw holes. The left one has the "AT" etched near it:

My trusty Socket 5 motherboard :

The board in the case. All screw holes have a perfect fit. All expansion slots are taken up without difficulties :

The ATX-to-AT power connector convertor with switch :

Contents :

P133 on a Socket 5 Unico Ve-501 Pentium motherboard,
256MB 72-pin FPM DRAM
Rendition Verite 2200 PCI
SB 32 PnP (CT3600) ISA

Back view:

The I/O opening can be covered with any cardboard, and keep the AT-Keyboard connector exposed.

This mobo doesn't have ATX power connector. So the only way to start up the machine is via the AT-Switch through the converter.

Other socket 7 and ss7 though, can be more useful, since most later boards came with ATX power connector.

Some of the cases supportin E-ATX have 8th expansion slots. For example http://www.lian-li.com/v2/en/product/product0 … index=61&g=spec Any information about these kind of cases supporting AT?

I just looked up several 8 slot ATX, and none have punchouts for D-SUB. If you're going to need to do tinwork regardless, it may make as much sense to get a more common 7 slot with punchouts and add the 8th slot.

Do you have a favorite style or brand of case already, Jakodemus?

(Edit: wrong name)

I could take a look at the cases in my attic, but even if I have 8 slot AT-compatible cases...I have no way of finding out the model and original manufacturer of the case anyway. Best I could to is post pics and maybe someone will recognize it.

Malik wrote:

Alright, here's my recent experimentation with my ATX case with AT-compatible screw holes and an AT motherboard

Very nice!