PC powers up, but that's it...

[Neken]

When I turn my PC on it all seems to power up, but then nothing at all happens. The MB lights and all the drives power up along with all the fans.

It then just sits there. No bios beeps, no screen, nothing.

Because of a previous intermittent problem that I put down to the motherboard, I've replaced that thinking it was connected. No intermittent problem so far, but still won't do anything after powering up...
As there was no signal to the monitor, I switched the GFX card. No change.
Switched the memory. No change
Unplugged the IDE hard-drives, leaving the SATA - no change
Unplugged the SATA hard drive, leaving the PATA - no change

If the CPU's dead, the board will just fail with some beeps at the bios, yes?

I'm plumb out of ideas so any of yours would be welcome.

NF7-S, Tagan 580W, 2x512 Corsair PC3200, XP-M 2500+ (2.2GHz), R9800Pro-AIW, 3xHD, 1xDVDRW, 1xDVDROM

 

[Neken]

Connectors: I believe they are all secure.

The PSU is a new one as the last one blew, but the machine has worked at least once since it was installed. I'll see if I can power the main machine from my second one's power supply without physically swapping them. Hopefully that'll be easier than taking out both heatsinks and fans to get the PSUs out. Daft design IMO!

Ta for the replies and any more suggestions - my work continues

 

[Neken]

Thanks to all those who suggested solutions - turns out the board was sent to me with the CMOS jumper set to discharge. Put it back to normal and all's well