Well, I didn't know..
High powered video cards are a waste for trading.. too much heat, noise, $$$.
Probably the best trading cards for 4 monitors would be, 1, Nvidia Quadro NVS 285 PCIEx16 + 1, 285 PCIEx1.. or 280 PCI.
No fans, no noise, high quality display. I've watched movies on these cards, and they're great for that too.