HIS Radeon 4670 HDMI Output Video Blinks

Hey,

I've browsed through the troubleshooting of these radeon 4600 series cards and havent found a problem quite like this...

I'm getting a blinking from my HDMI output on my HDTV. It'll kinda blink green on the bottom third of the screen, then totally black out for a second or two... and does this every 10 seconds or so.

Worth noting: The DVI output works fine, I'm using a dvi to hdmi converter (using the same HDMI cable as before) and no problems.

Also: When i installed the card, before i installed the drivers for it, It worked, Albeit at an extremely low resolution.

Any thoughts?