Occasional black screen.

[frza]

So I finally got my hackintosh to work! - The only problem so far is an occasional black screen that lasts for 1 second and then goes back to normal. What could be causing this? I'm using the onboard Intel HD4600 graphics and it must be contributing something to this.

Specs: Dell optiplex 9020 USFF - Dell (intel) motherboard - CPU: Intel Core i7-4770S - iGPU: Intel HD4600 graphics.

Thank you.