No Signal for Monitor

Basically, my monitor does not have a signal when I boot up my computer. It might be my motherboard, but im wondering if there is anything else it could be because then i'd have to replace my liquid cooling system along with it.

Specs:

• Intel Core i7 920 2.67
• 12GB DDR3 ram
• GeForce 9500 GT (other card is GeForce 250S)
• 800 Watt Power Supply
• Windows Vista Premium 64bit

Things i've tried:

• Reseating RAM, Video card, CPU chip
• Different monitor/power cables
• Different video cards
• Different pci slots
• Different monitors
• Different Power supplys
• Took out Battery for a few mins (maybe longer?)
• Ran the system for ~10 hours

Things i've noticed:

• Correct color lights light up on motherboard for the different modules
• System runs normally
• USB devices dont light up

 

any ideas?