Check out what I just got! It looks like an SBC, but it isn't... not exactly. I mean, it kinda is.

So it's got a CPU here, some power regulation, and some RAM.
So this is definitely at least partially a computer.

And on the bracket we've got sound, VGA, and USB.

So here's the spoiler for what it is:
It's a SunPCi!
This is a PCI board you put inside your Sun workstation to let it run PC software. Instead of running a VM in software, this is basically just an entire PC on a card.

On the back this says it's the "Penguin" model.
PWA-SunPCi Sun/PC+M BD

So let's see what's on here.
We've got an ESS AudioDrive ES1869F.
That's an all-in-one 16bit soundcard chip. It's got OPL3 support, IDE CD-ROM interface, MPU-401 emulation for MID, support for a game port, and an external DSP to let you build it into a modem.

A Winbond W83877TF I/O chip.
This can control floppy drives, serial ports, parallel ports, IrDA, and handles ACPI & IRQs for a plug & play system.

Near that chip we've got a TI SN75185, which is an RS232 transceiver.

This big intel chip is a PCI-to-PCI Bridge for embedded applications.
Basically this lets you plug two PCI buses into each other, and it'll handle things like message queuing and mapping different address spaces into each other.

EliteMT LP61256GS-8.
I couldn't find a specific datasheet or reference, but from the name, this is a 32 kilobyte cache SRAM

It's next to this bigger similar looking thing, which is supposedly 64 megabytes of SRAM?! that seems... a lot.

Over near one of the EEPROM chips we've got this W48C67-01H. That's a clock generator for Pentium & Pentium II chips.