My new configuration does not start

I start a new configure (complete) and it does not start

Everything is connected (usually) but when I put the food turned the motherboard does not light (no diode), I told myself that this map can be no mere diode saver, but when I turn on the CPU:

The power supply fan of running
My fan turns back
The LED lights of the CM

fan but the trial does not start and after 2 seconds reboot the PC.

I tried unplugging everything and leaving only CM + ram (I also tried without ram), and it's the same thing.

Can someone help me..?

you are about to have everything connected? 24 pin, 8 pin, CG ...

you have something on the screen or nothing nothing?

I forgot to put this :

CASE: Antec Sonata 3
Motherboard: Gigabyte EP35-DS3P
Processor: Intel E7200
Memory: Corsair Twin 2x1go 6400
HD: wd 250GB 16mo
Graphics card: twintech GeForce 9600GT

The 24 pin is connected, and I do not have 8-pin, but a 4 pin is connected.
I plugged the GC but it would not start I unplugged to test if the motherboard starts.

Ideas in bulk (some really basic but sometimes it's so evident that we think not):

You plugged all the cable feed on your CM?
The heat pipe is it mounted? Is it connected?

Tests outside the box with minimum: Alim CM + + CPU + RAM + CG

All cables are plugged a priori
- The heatpipe is mounted and connected to the CM (I tested with another heatpipe and fan did not start either).
- LF + litigation ram = No BIP, ca 2 seconds boot and reboot direct

Test what I say: assembling and externally to see.
If the same pb, you try first with another food, and other other CG RAM and other CPU (if you can do all render it). If still nothing, your CM is defective.