I will give a little information about my setup, I have a Dell PowerEdge T710 with (2) XFX R5 2XX (HD6450) GPU's with (2) Jaton USB3.0 PCIe add-ons. I have (1) GPU and (1) USB add-on passed through to a Windows 10 guest, and the other GPU and USB add-on passed through to a Linux OS. ESXi 6.0 Host.

The Win10 environment works flawlessly. The Linux OS on the other hand I can't seem to get it to light up the heads. I have tried Ubuntu/Fedora/RH/Gentoo/ArchLinux and even a custom linux build. In all of them I can get the kernel to detect the card, compile the catalyst drivers and have them recognize and the card, but I cannot get Xorg to start because it seems to think there are more heads on the card than the card can support.

I am talking to the Vi0L0 (whom is the unofficial catalyst portage builder for ArchLinux) to see if it is something stupid happening between the vmwgfx driver and fglrx driver. Was hoping this thread had some interesting insight, but it appears not so much. If anyone develops some work arounds, let me know.