PC won't get past BIOS when any graphics card installed.

ekke.einberg

Prominent
Jan 26, 2018
1
0
510
I had an power cut at my house and after that PC hangs on BIOS splash with 1 long, 2 short beeps. Tried different, brand new graphics card - same story. Tried different PCI slot - same. Tried different PSU - still same.Cleared CMOS. DIsconnected all peripherals. Nothing.
But WORKS PERFECTLY with on-board video.
Mobo is GA-7zzx-d3h, graphics cards GTX970 and 1050 TI.

Looks like a motherboard problem, but the again how can it be broken in a so specific way?
HELP!