Such cards can only be used in backplanes. Using it in an ISA slot of a normal motherboard will cause bus fighting between the CPU card and the motherboard, potentially resulting in physical damage.

The stuff in Amiga is specifically built to allow such functionality, any random thing isn't gonna work.

Actually, it depends whether it's a CPU card for a backplane or a companion card for a normal PC. The later ones were mainly used in systems of different architecture (Apple, Sun, etc.), but they do exist for PCs as well.

If there's a live CPU in the regular motherboard, you're asking fo trouble. But if you don't have a backplane and you do have a motherboard with an AT-style power connector and either no CPU or completely dead CPU, chipset or BIOS, you can use the dead board to power the SBC. It may even be able to use some or all of the other ISA slots and onboard ISA devices, depending on wiring.

You can even use a larger PICMG SBC (i.e. one with PCI and ISA inline behind each other) if it physically fits, although you can't use the PCI connector and you have to be sure that the PSU and ISA power lines are capable of powering the beast (486 or Pentium 1: usually OK. dual Pentium 3 or later: probably not).

You can have a bit of fun this way, adding an impossably fast CPU (usually with similarly modern VGA and I/O onboard) to an old dead OEM system.

Hamby wrote:

What happens if you plug a (in this case 486) CPU card into the ISA slot of another computer?

Also, FYI - Powerleap Renaissance cards.

Once a time there was a SBC like "upgrade" card that actually could "parasite" a 486 board, taking over the board's CPU, and making use of host board bus and peripherals.
It wasn't x86, but MIPS CPU driven, and it wasn't a pure ISA card, but a VLB one.

It was the Shablamm! Nitro+ VLB. This is the only time I could see an actual upgrade card in the true sense, as how them work in the Macs and Amigas. This board is actually a sort of Unobtanium, but in a very old eBay publication, before they upgrade their look to the bloated one they have now, there were some pics of it working. Looks like is even possible to switch between the card and the host 486 at boot time without physical switches.

I suppose such a thing would rely on ISA bus mastering where it can politely take over the machine.