Hi Zjenep, thanks for the reply.
Yup - same bios, same motherboard - z68 Extreme 3 Gen3. BIOS confirms the model and current BIOS version - 1.20.
Tried three USB sticks today, all formatted as FAT32 and all tried in both USB ports at the back of the tower.
And yes, I am unizpping the archive, tried - 2.10, 2.20, 2.30 (all available for the mobo).
Even partitioned my HDD, small partition, FAT32, copied, zip, unzipped, just to check - same message.
I've put keyboard on a front port, so nothing else except keyboard in the front and USB stick at the back... no success.
I doubt that I should remove videocard, RAM, etc.
Rest of the setup is:
i2500k
Radeon 7870
16GB RAM Kingston @ 1.5 V (4x4)
1TB HDD Seagate
1TB HDD WD Black
Oh and mild overclock at 4.2GHz, which was removed before I started update. BIOS is at defaults currently.
No troubles with the setup - everything runs smoothly, no blue screens, no fatal errors in log files.