AMD 6870 on DVI/VGA connection causing black blinks?

[XDroidie626]

i bought a AMD 6870 last year to put into my rig and i have always had this problem with it, if i run my VGA monitor which i prefer to my TV (Used TV for HD but it isnt as sharp as my monitor ofc) every now and again it will black out and then show the image again, the blackout lasts for around 1sec maybe 2 and then may do it a min or 2 later, it only happens in games never on my desktop or in youtube :S

Previous i had a Geforce 250 GT and used same connection setup to same monitor and it worked perfectly fine but since i got the AMD this has happened :S

So is it the wire? monitor? the refresh rate? ideas?

Thanks in advance!!!!