I have a Dell Inspiron 531s slim tower desktop. I installed an AMD Radeon HD 5570 graphics card that worked great the first day but then refused to boot. When powering on, the fan noise/speed would go into high overdrive for 10-20 seconds until the power just cut itself off. I removed the card and the system now powers on okay -- except that if it is standing upright, it will go into the high overdrive again but will immediately calm down if I lay the tower on its side. What does this mean and how I can I fix it? thanks!