i have found the problem, after hours of googling, and forum search. the main problem was, that my storage controllers were the nvidia storage controllers (from my chipset). I replaced the OEM (nvidia) SATA drivers with standard windows IDE drivers, restarted the pc, and hallellujah, optimizer is working, trimcheck says trim is working.
the answer to my questionis here:
What do I do if my computer lacks compatibility with TRIM? O&O Software