Problem with my graphic card

Hi, I have PowerColor ATI Radeon x1650 pro that i got from my friend because my last graphic card broke and could toss it to garbage. Problem is that whenever i try to play games (in my case League of Legends) after some time my creen will freeze, mouse pointer turns into weird rectangle and i can move it just up and down. After some time my screen goes black and monitor to the standby mode. Only thing i can do is shut it down by holding power button. In some cases screen doesnt freeze and just goes to standby mode straight away.
I dont think its my psu because i have 400w psu and on the graphic card box it says 300 is needed for it to work. I changed the fan on the card because i noticed its spinning slowly and not cooling at all with better one that works just fine but same thing is happening.
I noticed that my card might be overclocked because its memory clock is 750 and default (according to Riva Tuner) is 400.
I tried to underclock but my screen goes either blue or green and i must power button shut it down again.
It would be great if some1 could help me out.
Answer #1
I’m assuming all the drivers are up to date with your current OS(operating system)?
Answer #2
Yes, i tried that but still same thing.
Answer #3
Did you delete the display drivers from your other card before installing the new one?
Answer #4
Monitor the tempurates, it could be just the driver crashing (because it’s getting too hot). Make sure you have the fan increase with speed with the temperature increases (ie 1 temp. increase = 1% fan increase).
Have you underclocked the memory? Maybe that’s what causing problems.
Answer #5
when my screen went blue/purple my nvidia geforce 8400 gs overheated.
Answer #6
Well turns out my graphic card is some weirdo in the graphic card world. I cant monitor the temperature but i can tell by touching it that its scorching. Heatsink on the other hand isnt that hot. I thought new fan would fix the problem but apparently not.
I tried with the underclock but when i test the reduced clock memory screen goes into some weird colors and i must shut it down by holding power button. I find that strange because shouldnt it run without any problems with underclocked memory? Its not like i stressed it, its completely opposite….