Patch of mosaic on screen when mining with XFX HD7950?

[dennis97519]

I got a XFX R7950 Black Edition Double D with two DVI ports from 50btc.com. Only recently I have started mining with that card and even with the stock clock of 900 MHz I get patches of colour not blended with the screen appeares. If I overclock it slightly(to 950 MHz) the driver will crash. Also the hashrate is only 436 MH/s on average. And the temperature always get over 70 degC. I have a 760 W seasonic power supply.
Is the patch of colour because of overheat or what?
 

[dennis97519]

I got a XFX R7950 Black Edition Double D with two DVI ports from 50btc.com. Only recently I have started mining with that card and even with the stock clock of 900 MHz I get patches of colour not blended with the screen appeares. If I overclock it slightly(to 950 MHz) the driver will crash. Also the hashrate is only 436 MH/s on average. And the temperature always get over 70 degC. I have a 760 W seasonic power supply.
Is the patch of colour because of overheat or what?
 

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[dennis97519]

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