Dual screen and Graphics card issues

Hello and thank you for taking the time to help me.

I used to have a 5850 and after having many problems with it and multiple times of reinstalling the OS and even replacing everything in my computer other than the PSU, I still had problem so after a few phone calls with Sapphire I got a replacement 5870 and I was very excited!

After a few weeks with the card I am still have issues with the new one and things aren't looking good
I want to run dual screens and for now it works but every time I do something that involves a small amount of GPU usage the screen gets streaks and flickers and after like 2ms goes back to normal (usually happens when I watch youtube or what not, I'll upload a video later today so you can see what i mean).

So my main question is, Is this just bad luck with my graphics cards or something else? Im trying to get my hands on a 570 from a friend to test and see if its that.

Also, When I have two screens set up and I OC the GPU it flickers and what not all the time and not only when I play videos or open a webpage.

Hope you can help me, Thanks again!
Light.

Sounds like a power supply problem, whats the make and model of your current one?

This is my PSU
http://www.newegg.com/Product/Prod [...] 6817341019

I dont know if this has anything to do with the problem I am having but any VoIP I use like Skype, Mumble, TeamSpeak and so on gives me problems at what sometimes seems randomes times but also when the computer is working such as when I am in a mumble chat with 4 people and playing bf3, the sound from mumble laggs only when the next maps is loading and not during the game.

Thanks again to both of you for helping me with this!

The video card issue occurs here and there when its not OC'd but as soon as I OC it even by 1mghz, It starts freaking out

The VOIP issue happens when at random time from what I can tell because I was just in a game and when the level loaded it didnt lag.

My CPU temps are in the mid 30's and im running an i5 2500k so how can that CPU not handle it selfe ?

And regarding the Graphics card, I think you are all right it is the PSU