@Gosa: I suppose I am still confused as to your situation. Correct me if I am wrong on any of the following;
1. Your system behaves correctly when using the 3345 driver
No, never. Not even when used older drivers.
2. Your system behaves incorrectly (no HDMI, DP, DVI - but VGA works) when using the 3379 driver
Taking in account that I'm currently on Windows 7 Enterprise 64bit, I can not update driver to 3379.
But I can try installing Windows 8 and try with that driver.
The picture is significantly better with DVI that with VGA cable. But, when PC is restarted, there are no initialization of DVI or any other port, only VGA.