a sandwhich :
Stated above that I tried it in a wall socket as well, minus the ups. No change. I take it the psu is bad? It is a year old corsair 850 tx.
Sometimes it does happen, for no apparent reason. It's happened to me. Only wild speculation will give you the "truth".
As best as I can figure, the PSU has had a power surge of some sort and the whole rig is dead, the only thing that might still work would be the ram and the hdd, the motherboard and the PSU has carked it. That's what happened with my phantom issue. Although you still get a glimmer of life from the PSU, it doesn't last long, only a moment or two.
You could try reseating everything, thermal paste, reseat the cpu, disconnect all the cables from the motherboard and test just the cpu, ram and psu, you might get life but I doubt it. Try replaciing the PSU with something similar or less watts. Remove the graphics cards and use onboard video out, remove the cmos battery for 10 seconds to reset the defaults.
Nothing you do seems to work with these phantom issues but at least you can try, you might actuially find the problem yourself. Report back here when you do.