Firstly, please excuse any idiocy you find below. This is my first build, and I'm sure I'm just being dumb.

The setup is a Gigabyte GA-8I945P Pro mobo with Intel Pentium 4 630 3 Ghz.

The crappy 300W generic power supply supplied with the case works fine. However, I didn't want to rely on a cheap psu as on my last system the power supply failed and my mobo and graphics card were fried.

So I bought a 550W psu with all sorts of component protection features, plugged it in, and it didn't work. The motherboard and keyboard lights were on, the fans moved a touch and then stopped, and the power switch (case) wouldn't do anything. I assumed the psu was faulty and returned it.

I then purchased Hiper 480W Type-R Black PSU, (different brand altogether than the first one) again with component protection features. This did exactly the same thing. The 300W cheapo one still works fine.

I took the Hiper psu into work and plugged it into my work pc - exactly the same thing happened - power seems to be going in, but it isn't allowing things to startup.

Is there something I need to do to these component/voltage/circuit protection type of power supplies? It seems as if it shuts down right after putting current through the system, which suggests it is doing so to protect it, but as I say, both computers work fine with cheaper psus.

Any thoughts on this would be greatly appreciated. Sorry for the longwinded explanation.

Did you try to switch the PSU on (just above the powerplug)?
I have the same Hiper PSU and it works like a charm!
Did you check for the right input voltage 115/230?