Power Supply Problem

[kmac]

Bought a new power supply from Scan -a Seasonic S12II 380W Bronz for my AMD Athlon 1.4Mhz system.

It replaces a corsair HX620 which I need for a AMD triple core build.

However, on replacing, a little green light illuminates on the motherboard but the system doesn't start - no CPU fan no case fan nothing. I put the old Corsair back in and voila - all works. Put the Seasonic back and only get little green light on motherboard.

I'm thinking this may be a faulty PSU - any other suggestions before I RMA?

[kmac]

Rather bizarrely, tried the PSU again this morning and it fired up first time. So, alls well that ends well, but a bit of a mystery as to why it wouldn't work yesterday. Maybe I tripped out some overload setting?

Thanks for looking.