|I know what a GPU is and it is 450W minimum.|
That PC building guide is a lot more detailed than the one I went by. Since I've never had to handle installing one previously, I'm wondering if you can tell me whether there could be anything that wrong with the CPU. I felt that "power phase 4" was confirmation of the CPU responding. If not, I think that may be the thing to investigate, as I'm used to everything else.
So by bench test you meant running at minimum requirements? Yes, I've done that. I did it again, removing the hard drive and a fan. Still nothing on-screen. The same thing, screen reacts to the computer starting and the GFX card fans are running fine. Everything is brand new and out of the box, especially the RAM which just arrived today (I built the computer without it and tested booting, which gave the same problem - decided I'd wait for the RAM before doing any real tests).
And no beeps when the PC speaker is plugged in, either.