Hi,I am back to report what is going on.After I received the suggestion,I wrote an email to Antec asking for technical help.He gave me the same suggestion that PSU is not power enough.Cause my PSU have two 12v rails,and the CPU and GPU share one rail,might causing this problem.I also found that maybe the tower fan has some impact(I installed 8 fans and two directly to the Graphic card)I also tested the new 260 drivers,it got the problem worth,I would not install until the WHQL version publishes.My friend use almost the same components as mine,but his system works well when his PSU has only one rail with 40A,600w(His cpu is even I5 750).
So I made two changes:
1.I install a separate PSU supplying power to the graphic card(Actually I test the power supply,when I run furmark and read 150W maximum.)
2.Shut two fans.
Now is better for use,but still sometimes it happens when I boot a game or a HD video,but very few times.However I never get blocked on welcome screen.That is what I feel much happier.
So I would not recommend multi rail PSU for using this system.600w is recommended.