Found @ a local ad site a lot of 8 motherboards for the low price of 5€. All untested. I assumed they would be dead, and it would be ok if one could be salvaged.
The firsts motherboard is an DataExpert EXP8551 Ver 1.1:
EXP8551.jpg
Not booting, beeping weirdly and the post code E1 (AMI Bios). In the manual of my post card had no such code for AMI. Luckily the theretroweb.com had a alternative Bios. Picked the Award bios, and the post code C1 came up.
C1 points to "Memory presence test; OEM specific-test to size on- board memory. Bad SIMM.". After tracing all probable culprits, found network resistors in opened circuit, namely RN1, RN2 and RN3. After replacing them the motherboard booted normally.
Next, a Epox P55-VX:
Epox P55-vx.jpg
Dead, no post, no signs of life and no shorts. Having an EEprom and considering the "time frame" of the probable use, I suspected a Chernobyl "type of a thing". Hunted down a version on the far corners of the web (no available bios @ theretroweb.com). Found 2 different versions, courtesy of "The wayback machine" and www.bios-mods.com . One from the old site of Epox, the other a patched version for the support of large HDD. The mobo booted normally with both Bios.
Next, a Shuttle HOT-681:
Hot 681V13.jpg
Dead, no post, no signs of life and no shorts. Suspected Bios, and after re-flashing, it booted normally.
Next, 2x Biostar P4M900-M4 :
P4M900-M4.jpg
Unusual combo, socket 478 + Pcie +DDR2 in a "gaming colored theme" motherboard. Both booting normally. Also noteworthy is the metal backplate for the cpu cooler.
Finlay a pair, P4S800-MX and a P4V8X-Mx, both from Asus:
2xAsus_P4.jpg
Unremarkable motherboards, but fully working.
There was also a 775 Dell motherboard, but due to bent pins on the socket and proprietary design, I had to scrap it.
All in all a very good haul.