I just checked my Nvidia rig and it has once again Down clocked. First to 405 then to 51

These are my settings on one card 898 1790 Voltage at 1000, 855 voltage the same 1000. Both cards are identical Asus Engtx460's Was wondering what voltage everyone else has their cards set at. I'm going to go back to 266.77 or 266.58 and hopefully this will stop happening. Any help is appreciated.