|"I got a sentey ERP750-SM 750W power supply"|
The Extreme Rock Power SM series is made by Super Flower for Sentey. Unfortunately it's not 80% certified but it is a good quality unit.
"I only overclocked the cpu but that is managed whatever i do never goes above 70* celsius"
How much did you overclock? Over 4.5GHz? If not, your temp under load shouldn't exceed 60C. And if it's a milder overclock than that, your load temp should be closer to 50C. If your temp is close to 70C, either your heatsink is clogged, it isn't installed correctly, or it's undersized for your CPU. See the following, especially the last entry: