Problem with new system - no boot

[Pogue]

Ok, so this is what I bought ..

Gigabyte Z170XP-SLI - Intel Core i5 6600K
Gigabyte GeForce GTX 960 OC
Crucial BX100 250GB SSD
EVGA Supernova GS 550W '80 Plus Gold' Modular Power Supply
Corsair Vengeance LPX 8GB (2x4GB) DDR4 PC4-24000C15 3000MHz
Alpenföhn Matterhorn Black CPU Cooler
Toshiba (7K1000.D) 1TB SATA 6GB/s 32MB Cache HDD -
OcUK 24x DVD±RW SATA ReWriter

I haven't built a PC for about 9 years so I took my time with this one but it just will not boot up. I have taken it all out of the case so all I have is PSU, MB, CPU, COOLER, HD, 1 stick MEM and DVD Drive.
The fans will turn on, the HD spins as does the DVD drive but I have no signal to the monitor and no beeps. I tried fitting the graphics card but it makes no difference, I have tried 2 monitors, 3 cables.

Any ideas?

 

[Pogue]

Yes, I have the bigger 24 pin connector and the smaller 8 pin connected.

I have tried the onboard graphics and the gigabyte card, still no signal, graphics card has only one connector that I can see.

 

[Pogue]

I have tried HDMI and VGA.
Will clear the cmos now.

 

[Pogue]

Aaaand, we're booted

Took it all apart and refitted the cpu and it now seems fine, many thanks for your help.