I recently bought a new CPU cooler, and installed it. After I finished and booted up, I had no display, not even the BIOS screen, but everything else is working just fine inside the case. All fans, GPU fan, etc are working. my GPU has a red LED warning, if I don't have the PCI-E plugged in, and that light is currently off, so I know It has sufficient power. I just put that GPU in this computer that I'm currently using, and it works just fine. I bought the same Motherboard off amazon, thinking it was a MB issue, as my friends suggested, but I am getting the same result on the new MB. Could I have tightened the CPU cooler to tight? Note that I have had this build since August 2012, and the only new addition since then was the CPU cooler last week, and the case, but It was working in this case before I installed the CPU Cooler. The computer I'm currently using to write this, is using the same CPU cooler. I installed it on both. Works great on this computer.
GPU: http://www.amazon.com/Radeon-XFX-6970-Graphics-Card/dp/B004GCIZ5A/ref=sr_1_6?s=electronics&ie=UTF8&qid=1396831097&sr=1-6&keywords=xfx+radeon+6950
MB: http://www.amazon.com/gp/product/B00539LP34/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1
CPU: http://www.amazon.com/gp/product/B005UBNKZG/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1
PSU: http://www.amazon.com/gp/product/B0055EIIXW/ref=oh_details_o01_s00_i02?ie=UTF8&psc=1
RAM: http://www.amazon.com/gp/product/B004E0ZKLQ/ref=oh_details_o03_s00_i01?ie=UTF8&psc=1
Case: http://www.amazon.com/Thermaltake-Level-Super-Gaming-Modular/dp/B005F7794S/ref=sr_1_1?s=pc&srs=2530613011&ie=UTF8&qid=1396831203&sr=1-1&keywords=thermaltake
CPU Cooler: http://www.amazon.com/gp/product/B00EBYYW28/ref=oh_details_o01_s01_i00?ie=UTF8&psc=1
GPU: http://www.amazon.com/Radeon-XFX-6970-Graphics-Card/dp/B004GCIZ5A/ref=sr_1_6?s=electronics&ie=UTF8&qid=1396831097&sr=1-6&keywords=xfx+radeon+6950
MB: http://www.amazon.com/gp/product/B00539LP34/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1
CPU: http://www.amazon.com/gp/product/B005UBNKZG/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1
PSU: http://www.amazon.com/gp/product/B0055EIIXW/ref=oh_details_o01_s00_i02?ie=UTF8&psc=1
RAM: http://www.amazon.com/gp/product/B004E0ZKLQ/ref=oh_details_o03_s00_i01?ie=UTF8&psc=1
Case: http://www.amazon.com/Thermaltake-Level-Super-Gaming-Modular/dp/B005F7794S/ref=sr_1_1?s=pc&srs=2530613011&ie=UTF8&qid=1396831203&sr=1-1&keywords=thermaltake
CPU Cooler: http://www.amazon.com/gp/product/B00EBYYW28/ref=oh_details_o01_s01_i00?ie=UTF8&psc=1