Cheers all, I think I'll go for the Gigabyte. The reviews on Guru 3D are excellent.
One more question.
It says it has 6 and 8 pin connectors. I take it these both have to be used. My old Corsair 620w PSU only comes with 6 pin PCI-E cables. What can I do? Are the cables available?
As Stulid mentioned you will need to use both, like my HX 620w PSU this only had 6 pin connections so you will need a adapter like the cable below:
Corsair did do a spate where you could apply for a 8 pin cable set.
https://www.overclockers.co.uk/showproduct.php?prodid=CB-034-AK&groupid=1929&catid=153