Power Supply fan works with paperclip but does not turn on with Motherboard

[mobu]

I have recently bought a Solid Gear 850W ATX power supply from Amazon (model: SDGR-850E). Upon connecting the PSU to the motherboard for the first time, the power-up LED turned on and then off quickly. The PSU fan didn't move at all.

After I unplugged all the wires and cables and powered up the PSU again, nothing happens. No LEDS, nothing. I double-checked my wires and everything seems to be in the right order.

Paperclip Test: Passed
I followed a tutorial (]http://dodji.seketeli.com/downloads/shuttle-psu-paper-clip-test.pdf )to jump start a PSU by using a metal paperclip and the fan turned on alright.

PC Specifications

• 
  Motherboard: Gigabyte Z68X-UD3H-B3
  CPU: Intel Core i5 2500K @ 3.30GHz
  RAM: 8.00 GB Dual-Channel DDR3
  GPU: AMD Radeon HD 6750

Images
http://imgur.com/a/I4k8t#0
I have taken a series of images to help you guys help me better.

I am confused with which cable goes into the 12V ATX connector? I can't tell the difference between PCI and the ATX connector

Thanks a lot for your help!

 

[scout_03]

follow this and check psu are yellow cable http://www.solidgearusa.com/files/ProductFile_en/PF_File/PS2%20Data%20Sheet_V3.pdf

 

[mobu]

follow this and heck psu are yellow cable http://www.solidgearusa.com/files/ProductFile_en/PF_File/PS2%20Data%20Sheet_V3.pdf

Thanks. I just tried the cable and it was actually mentioned on the back of the box. I am now 99% sure that the PSU was DOA

 

[scout_03]

did you try it in another system to confirm that psu is out .

 

[mobu]

did you try it in another system to confirm that psu is out .

I haven't yet. I just checked that the PSU ATX is v2.3 and my old PSU (that works with the mobo) is v2.2. Do you think this could be the issue?

 

[scout_03]

does the old psu made the system boot .

 

[mobu]

does the old psu made the system boot .

Yes it does

 

[Dark Lord of Tech]

Solid Gear PSU's are very poor. Invest in a better power supply.