GPU horizontal lines at login then freezes

[EatPeat]

Hi,
I am stumped here,need help to troubleshoot and finally arrive at a conclusion that what has to be done.

Few weeks back during gaming I encountered horizontal lines ,immediately after that my computer froze and there's the start,problem still persists.

Steps I took

Reseated my card,removed dust(normal cleaning).

Bought power supply tester Amazon.com: PC Computer 20/24 Pin Power Supply Tester With PSU ATX SATA HDD Connectors: Computers & Accessories
but it seems to show that
PSU graphic supply is working.

Installed fresh windows again but still issue remains

Did memory testing with windows memory diagnostic.


Now if I unistall my graphic card drivers,card runs as VGA adapter with no issues (limited functionality can't run games) but as soon as I install drivers the next boot immediately at login horizontal lines appear and then followed by freezing.

I ran my display on igpu ,everything seems to work fine all graphics n little bit of games n stuff.

Now I am confused and need help ,should I think that my graphic card is dead or before coming to that conclusion I should apply thermal paste n try that option.
I am also not sure somewhat power issue might be causing it but as stated above it was tested with at instrument and works fine. (Or do I need to check something else as well).

Components in my PC

Amd 7850 2 GB sapphire HD graphic card SAPPHIRE Technology
Cooler master 600 w thunder PSU.Cooler Master: Thunder 600W

 

[RoasterMen]

It's definitely time for your GPU to be replaced because your HD 7850 is dead. Your PC will turn itself off when the PSU cannot give enough juice to power up the whole system.