換左display card後mon不能進入power saving mode

本人用緊Dell U3014,但係早幾日換左張Zotac 980ti amp extream怪事就黎啦,部機熄時正常個Mon會即時進入power saving mode ,但係而家就係個Mon到寫 no dvi connection,要等五分鐘先至得。我有駁過第二個Mon試又正常喎,然後又試過用翻舊卡又冇問題,有冇人可以幫下我呀?都唔知係Mon定係display card問題