DVI vs HDMI or possible graphic card problem? help

OK so today after cleaning my computer and gtx580 graphics card (because of collected dust), i turned back on my computer and monitor would say that i have no signal.so i restarted thinking maybe it was a bug or something.but again same thing.so i took out gtx580 and put it back in ,checked if everything is connected right, and then it worked for 5 minutes while playing Battlefield 3 and then everything froze and sound was just steady buzzing. then i forced to turn off my pc,rebooted and same thing would happen just black screen with no signal. so since my gtx580 is fairly new (bought november 2011,only fan settings modified so it runs cooler) i thought there should be no problem with it,cuz i never had any problems before.temps never go above 82C. so i thought that there might be problem with the hdmi cable(with adapter to mini hdmi for gtx580). so i changed it to dvi.

so now playing Battlefield 3, it looks more grainy and colors are with more contrast,so black looks too dark and white looks too bright. i have been playing this game for a while so i feel like i really do see the difference. did i mess something up while carefully cleaning stuff (i didn't break or damage anything as far i know),did something happen to my gtx580 or does hdmi really differ that much from dvi ?? (i know dvi and hdmi are essentially same digital picture quality but still it annoys me)

please let me know what u think