Tacens Valeo V Power Supply 900W 80 Plus Silver Modular damaged with two s3
Thats because its silver grade.
Please stop giving incorrect information to new people. That makes 2+ people who are now incorrect (or stupid).
The +, 80+, Bronze, Silver, Gold, Platinum ratings on PSUs are somewhat arbitrary and maufacturers fudge (make up) their ratings. A Seasonic Bronze (which is lower than Silver) that puts out 800W could easily handle 2 S3s. If it was an 850 it could handle both overclock. A Seasonic Silver 850W would be fine
http://www.newegg.com/Product/Product.aspx?Item=N82E16817151083What matters is the manufacturer of the PSU. Seasonic is like the Mercedes Benz of PSUs. The rating just tells you roughly what to expect from the AC/DC conversion efficiency.