@ZyBeR
whot! this is "weird" seen that you have tryed another 2 CPU board!!!
Have you checked to have the right standoff for your CPU card?
A4000T were bundled with too long standoff . . .no problem with a 3640
but with a CS or CSPPC, this could be a big problem.
There are some useful pictures here in the Gallery.
Thanks to X-ray :-)
http://www.amiga.org/gallery/index.php?n=873