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So, my problem is next: I have a used mobo 990XA-GD55 and Gigabyte R9 290X. Both items are working, however, mobo can't see this videocard, I hear 1 long and 2 short bios signals.But if I wait for 3-4 minutes, I'll see Windows home screen. Still, there is some unstable work and PC can freeze...

I have installedthe mobo and the ram and the psu but now when it comes to connect the cables from the PSU, there is a big connector that has MOBO on it and then that splits into two connectors. So does the big end of the connector, solid piece, go to the mobo or the other way around. I couldn't...