GTX 560 not getting detected

Hello everyone,

I am trying to set up an enviroment for 2 GTX 560 (ENGTX560 DC/2DI/1GD5 and ENGTX560 DCII OC/2DI/1GD5) cards. My PC has only one x16 PCI-E slot. So, I am using an external converter that converts from x16 PCI-E to x1 PCI-E. To have enough power, I am using three PSUs for my system. One for my PC (300W), two for GTX 560 cards (520W and 420W).

The problem is when I start my PC, there is only one card (connected on x16 PCI-E slot on mainboard) starting with. The another one was running too, but there is no signal to my PC and monitor. When I take one card off from mainboard or converter, the another one works normally. In the past, I had connected two 9400GT cards with this system and it worked fine. So, does ENGTX560 DC II refuse to be used with ENGTX560 DC?

My system: https://1drv.ms/i/s!AgbGejy5Z1h0sBEY00TCzl4IicsB

Is there anything that I am missing out ? Could you guys shed some light ?

Thank You.