My sapphire radeon 6850 1gb having 2 thick blue vertical lines.

I have 530w psu with core i7 4670 and asus z97k motherboard. As of requirements, a 500w psu is more than enough according to manufacturing site. But when i connect my 2 six pin molex connectors and start I get 2 thick vertical blue lines on my screen. What might be the cause of this problem. Any help will be greatly appreciated. I live in UAE so we don't have any repairing shop. Generally people just ignore and go for new card with these kind of problems.