my experience shows that a pci-e x1 card won't work if you use it in an x1 slot with other cards...
x1 slot only works if no other pcie-graphiccard is installed (maybe some boards support this, but never see something running on this)
so... your board needs 3 pci-e x16 slots and only the first needs x16 power supply.
for example i have 4 cards running on an msi 790gx amd board, only problem is if i use my "passive" card (with no extra 6pin power supply) in my x4 slot (or is it x1 powered, with9500gt - a pci-e x1 card should run in this slot)
somehow it seems the pci-e x1 slots are not really designed for (multiple) graphic cards
if you want to keep your hardware then try 2 graphic cards with a matrox triple head... so you also get 5 screens...
or maybe graphic cards with more outputs (mostly ati has more outputs expect some exotic geforce cards)
you can't use hdmi but normal these cards have display ports... you need extra adapters for this but then all works fine!
MainSys: Z77 UP5,3550K,32GB 1600 CL10,ATI5750, M3 128GB,4x3TB R5@LSI9750
VJSys 1: 990FX UD5,X6 1045T,16GB 1600 CL10,GTX285+8800GT+9500GT+7800GT,M3 128GB,2x1TB R0
VJSys 2: 890GX GD65,AX4 645,8GB 1600 CL8,GTX 650 Ti+8400GT,500GB Hybrid,3TB