Realize that both AP550 and ATX are same signals and voltages except fan if this one uses this.

All you do is map out the pinout of your AP550 voltages, power good and PWR_ON signal will be same. Then splice this to a seasonic modular harness then you can use standard ATX case from on now.
Use your multimeter to check voltages and signals. Take a 6 pin GPU connector and remap this also for the CPU's power.

Once you know, consider adding to the compaq power supplies pinout in my thread I created?

Cheers,

Around the millenium there was a bunch of "fat" mid tower, generic-ish beige-ish ATX cases, with about an inch clearance above the PSU. Typically would have 3 x 5.25 bays. So one of those and something to hack the hole taller would work if you wanna keep original PSU.

Am I correct in understanding that you wouldn't mind slightly modding a case for a larger rear opening, as long as there's room? I'd think that there must be some cases that use a bottom-mounted PSU with enough space between the PSU and the motherboard. Alternatively, the Corsair Carbine Air 540 has the PSU in its own section, seems enlarging the hole would be possible.

I think that Compaq PSU is a similar size to IBM PSUs from that era. I have crammed the IBM EPS12V PSUs into all sorts of midi tower cases. Antec/Chieftec cases come to mind. IIRC i could get two of the screw holes to line up properly.

Here's someone who managed it using the PSU fan screws as alternate mount points. and a bit of case modding.

https://www.voodooalert.de/board/forum/index. … 7355#post357355

Could it be the PSU is compatible with the Chieftec Dragon if you take out the ATX PSU mounting plate?

My IBM 300pl uses a PSU that looks like it matches this ones size. If you could find one of those for less ...

pentiumspeed wrote on 2021-06-27, 22:09:

Realize that both AP550 and ATX are same signals and voltages except fan if this one uses this. […]
Show full quote

Realize that both AP550 and ATX are same signals and voltages except fan if this one uses this.

All you do is map out the pinout of your AP550 voltages, power good and PWR_ON signal will be same. Then splice this to a seasonic modular harness then you can use standard ATX case from on now.
Use your multimeter to check voltages and signals. Take a 6 pin GPU connector and remap this also for the CPU's power.

Once you know, consider adding to the compaq power supplies pinout in my thread I created?

Cheers,

That pinout's already been done:
Re: Weird Compaq Motherboard
Couple of weird ones there, so not 100% certain it's all regular ATX in terms of behaviour.

BitWrangler wrote on 2021-06-27, 22:18:

Around the millenium there was a bunch of "fat" mid tower, generic-ish beige-ish ATX cases, with about an inch clearance above the PSU. Typically would have 3 x 5.25 bays. So one of those and something to hack the hole taller would work if you wanna keep original PSU.

Sounds very much like what I'd be wanting. Do you have any pics by any chance?

Oetker wrote on 2021-06-27, 22:19:

Am I correct in understanding that you wouldn't mind slightly modding a case for a larger rear opening, as long as there's room? I'd think that there must be some cases that use a bottom-mounted PSU with enough space between the PSU and the motherboard. Alternatively, the Corsair Carbine Air 540 has the PSU in its own section, seems enlarging the hole would be possible.

Slightly modding is no problem, what I'd rather not have to do is cut a PSU-shaped hole in the top of my case (most ATX cases I have) or saw away internal structural elements (my Cooler Master Stacker). Looking at it, the Air 540 would do the trick, although that is one HUGE (and expensive) case and a bit too modern for my taste.

PC Hoarder Patrol wrote on 2021-06-28, 02:30:

Here's someone who managed it using the PSU fan screws as alternate mount points. and a bit of case modding.

https://www.voodooalert.de/board/forum/index. … 7355#post357355

Nice. Something similar would be my ideal solution.

waterbeesje wrote on 2021-06-28, 17:40:

My IBM 300pl uses a PSU that looks like it matches this ones size. If you could find one of those for less ...

Now that would be a lovely mashup. PSU does look very similar (if not smaller, which is hardly a problem), however that 300PL isn't ATX but something between LPX and NLX with a riser board. That would add a whole new set of challenges.

dionb wrote on 2021-06-28, 21:51:

BitWrangler wrote on 2021-06-27, 22:18:

Around the millenium there was a bunch of "fat" mid tower, generic-ish beige-ish ATX cases, with about an inch clearance above the PSU. Typically would have 3 x 5.25 bays. So one of those and something to hack the hole taller would work if you wanna keep original PSU.

Sounds very much like what I'd be wanting. Do you have any pics by any chance?

The problem is a lot of them were nameless, this Chenming shows the layout pretty well... https://www.neweggbusiness.com/product/produc … m=9b-11-125-471 They were all pretty much identical inside and at the back with various bits of "flair" in having different plastics on the front, and maybe designs stamped into the side panels. Damn, you'd think there'd be a line of them still out there, they were everywhere, seems black is the new beige now, hard to be different.

Edit: Brits and Europeans might satisfy their beige lust here, http://www.evercase.co.uk/index.php?route=pro … gory&path=63_89 nothing that looks like it works for OP though.

BitWrangler wrote on 2021-06-28, 22:16:

[...]
The problem is a lot of them were nameless, this Chenming shows the layout pretty well... https://www.neweggbusiness.com/product/produc … m=9b-11-125-471 They were all pretty much identical inside and at the back with various bits of "flair" in having different plastics on the front, and maybe designs stamped into the side panels. Damn, you'd think there'd be a line of them still out there, they were everywhere, seems black is the new beige now, hard to be different.

Edit: Brits and Europeans might satisfy their beige lust here, http://www.evercase.co.uk/index.php?route=pro … gory&path=63_89 nothing that looks like it works for OP though.

Not too obsessed with beige, I'm all for function over form. But your suggestion about "three 5.25" bays" might just have been the tip I needed. I dug around and checked the one case I hadn't looked at before: a 1999-era Packard Bell Spheris II midi tower. Originally it contained an MSI MS-6168 uATX i440BX motherboard with onboard Voodoo 3. I've moved that to a smaller Packard Bell Squarius II uATX mini tower (uATX boards belong in uATX cases IMHO), so the Spheris was empty and unused. I had assumed it would be a very tight fit, but I assumed wrong: it has about a centimeter of unused space above the ATX PSU.

This morning I took a good look at it, grabbed my Dremel and removed a few metal supports from the underside of the case top. I'm now about 1mm away from being able to slide the PSU right up to the back of the case, and even as it is I can fit it, just a few cm behind the back. Still have some mm to spare above the motherboard, so this will work regardless.

Had to go back to work before I could continue (or take pics), but I'm confident I can get this to fit. Here's a pic of a comparable case, you can see the >1cm space above the top 5.25" bay, which is also present at the back:

Update:

Dremel cutting discs arrived so time to get to work.

Basically the operation consisted of cutting out a PSU-shaped hole in the top of the metal inner case, then carving out some new screw and power cord holes and finally trimming the inside of the plastic outer case so it wouldn't foul the PSU.

Just started:

End result for the metal parts:

Plastic on top:

Note that the plastic is filthy and is currently sitting in the dishwasher together with the other external parts to get all sprightly. I also gave the metal case a good vacuum and wipe, partly for aesthetics, partly to avoid conductive metal filings all over the place when I start to build.

Pretty satisfied with how it looks so far, only issue is that I had to cut through a reinforcing bar to get the hole snugly up to the back of the case. That means it's nowhere near as solid and you can see the topmost bit crumpling slightly when I screwed in the PSU.