Hello; This is my first post here. I have a brand new corsair hx850w desktop power supply, I bought it from someone so it is not under warranty. From the first time i plugged it in, it didn't start unless I give it a little tab or nudge. I put it in my pc case and used it normally, it worked just fine, and tested the voltages with a multimeter it was very accurate. Sometimes it won't start unless i give it a little tab. After like a month, it won't start with a tab, so i got the psu out of the case and then a tab it worked, but if I flip it over it won't work unless i put it back to the other side. After 2 days, it won't work whether with a tab or not or putting it on any side. I took it to an electronics repair shop, he checked it and told me it is still brand new, with no troubles whether in the board or any capacitors, he checked soldering points on the back of the board and the front, but there are no problems. He is trying everyday but can't seem to catch the problem. So the big question, what do you think the malfunction so i can tell him to check?, because @ that time he is open to all suggestions. Please help, the psu is still new and it is a waste not to work again. Thanks for your help in advance. Regards.