How do I permanantly fix my Xbox 360 with error e74 (red light on third quadrant)?

I opened up my 360 and pushed in the GPU more... I turned it on and it worked but during a lan party my system started hiccupping as in the gameplay started displaying black spots indicating E74 again... I restarted my system and it was fine but i didn't put any preventive measures in my 360. I need a way to keep the gpu strapped to the motherboard without having to solder anything and preferably under 20 dollars. please help and thanks! (btw i have a falcon board)