The dimming room lights do not sound good, as it might be an indication of a short circuit. But let's move along anyway.
First of all, disconnect your sound & graphics cards, HD, and Blue-ray. Leave just the mobo connected to the psu via the 24pin<->8+18pin & 4pin<->8pin CPU connectors(the left sides indicate mobo connectors, the right - psu). RAM seems unlikely to be the cause of the problem, but you can disconnect it as well for a good measure.
See if this bare configuration gets powered up. It should try to boot normally, and if you've got the monitor and keyboard plugged in, you should be able to access bios(or get a message that e.g. RAM or keyboard is missing).
If it works, start adding one device at a time and see where it takes you.
If it doesn't work, a short circuit between the mobo/psu and the case might be causing the problem. Take the mobo and the psu out of the case, put them on some isolator(i.e. not on anything made of metal. A carpet or a bedsheet would do.). See if the boot sequence starts.
Should it still ignore your valiant efforts, say fuck it and go for a drink. Maybe somebody else comes up with an idea while you're at it.
Oh, and by the way, the rear psu I/O switch should be on I, while the hybrid/normal switch can be left on whichever mode - it just slows down the psu fan when "hybrid" is on, so as to make the psu quieter while the power consumption is low.