Is this motherboard problem somehow?

All was fine untill one day my ex graphic card 8800gt did die when i was starting one game...i then replaced it first with hd 4670 and then 9800 gt and but no use...Problems started immediatly with new cards...when im playing games i get 1-2 secons long freezes what are very anyoing when im playing competitve games :S and longer the PC is on the more horrid freezes goes and can last longer and occurs more....Its not overheating cuz i have 2 fans inside case and one big desktop fan breezing air into the open case and 8800gt did work just fine. I did clean dust and uninstalled all drivers and re-intalled...no help. I did even re-install whole windows and no help...Only difference between these card is that 8800gt had exta cables to power supply unit but i cant think that would be the case..hmmm...Like 8800 gt did curse my computer when it died :S All if my joy to the gaming is gone now :S