the problem is that these PSu dont have 80+ certificate
i took one off(need to get a tester i think is dead) and put another that is certified (700w) now mining whit 5x5850
The 80+ certification means that the PSU is at least 80% efficient over all loads - in other words, to get 100W out it may pull 120W at the wall. Generally these PSUs are more than 80% efficient, with the highest efficiency between 50-70% of their maximum load. 80+ Gold PSUs are often 89%+ efficient at those loads for example.
Your non-80+ PSU should still deliver the quoted maximum wattage, but may be pulling significantly
more at the wall. If it's rated 750W, it should
deliver 750W without a problem. Of course maxing it out is definitely not good for a cheap/generic PSU, it will eventually burn out on you.
If that 700W 80+ PSU is running all 5 of those 5850's, you're really
close to max, if not exceeding it, which is bad for efficiency and probably worse for the PSU.