I have bought the corsair AX850 psu
so i have 2 problems
1) the 24pin power cable in the other end that connects to the psu has 2 seperate clips do i have to blug both or just the 20pin one?
2) there is no 4pin ATX12v connector!?!??!!?
What does your motherboard require?
20 pin?
24 pin?
If your board has a 24 pin socket...that answers the question...use both parts of the connector.
4 pin?
8 pin?
Many newer boards have an 8 pin socket, but will accept a 4 pin connector...although 8 is preferred.
The 8-pin connector will resemble a PCi-E connector...but isn't. It may either be a single 2x4 pin connector, or a separable pair of 2x2 connectors.
Your PSU should have a 4/8 pin connector for the EPS connector.
Yellowbeard's link shows them very nicely...