Did you find your way to this? https://theretroweb.com/motherboards/s/unknow … and-486-ver-1.0 not that it knows much more than you can figure out looking at the board.

Thank you. I was only 27 mins to late. But also found it there.

Also this one:

https://www.elhvb.com/webhq/models/486isa/4386c.html

Googled on Solution 4386C.

I'm not familiar with the "Solutions" brand, but since the motherboard itself uses the same name, I would assume that 88C4386C is just a rebranded OPTi 82C291, which was a 386/486 chipset which they called the OPTi 349 chipset.
The same chipset was used on the Everex Step 486 and Magitronic 602 486WB4A.B2.

I have made a bios dump from this board.. It doesnt exist on theretroweb.com.

Didnt test the board yet.. So i dont know if it works.
But it is a better plan to copy the rom first before put some current on the board and then rom getting bad. (so i archive it first before using the board.) then can always make a new one if something goes bad.

Does any have any idea if there could be an 386 cpu been used on this motherboard or perhaps a 486DLC chip?

I dont know how i have to install a 386 inside * it looks like a 486 PGA socket 1 to me*

This because the board is called 386 486

This schematic says in de middle of the board? So no PGA 386 cpus here can be installed?

In de middle is are two empty QFP pads on my board..

The typical deal with those type of boards was to sell them with an AMD 386 at 25 or so Mhz already mounted for like $5 more than a bare board, which was attractive for upgrading older 286, with a 486 option when chip prices dropped. Not sure you'll find a socket for that footprint, so yah, you'd have to solder it on if you wanted one. More likely to support the weirder chips because internal L1 handled for 486es, but maybe have to try it to find out for sure.

Is it true that this board is just a cheaper one?

From an other motherboard i taken of some 20ns 32k x8 chips for total of 256KB cache.. The cache on the board when i bought is wasnt there anymore.. So i guess somebody has taken that already
With the 20nS srams i cant set the board to 0 wait state.. Only 1 wait state will work.. But then the board operating kind of slow..

I have to look for another set of srams with 15 nS so i can set the wait state to 0.. I think it will help a lot to perform much better.

Also think with the jumper setting for cpu:

CPU TYPE CHOICE
===============

J10 J11 J12 using
---------------------------------------
short 2-3 1-2 486DX, 486DX2, P24
short 1-2 1-2 486SX, P23T
open open 2-3 486SX

I guessing the two settings with JP10 shorted is for the PGA socket cpu.
And Guessing the last one with Open should be for an QFP chip which would installed on the motherboard.

So that could be an 486 SX 25Mhz QFP one (big solder pad), or for the little pad an 386 DX 40 perhaps.

reminds me of the msi contaq 386/486 combo, which had sockets for both copro and cpu and is listed on stason.org - so they might have a manual for your solution board.