Yes, cleaned the Intel and AMD drivers with DDU and then reinstalled the Intel driver before installing the eGPU.
The 6850M is definitely disabled. It normally resides on the PCI-e x16 port that's directly connected to the Sandy Bridge CPU. HWiNFO64 shows the x16 port as empty when I disable the dGPU in the BIOS. It also doesn't show in device manager even with "show hidden devices".
There are three PCI-e x1 ports; one for WiFi(replaced with eGPU), LAN, and USB 3.0 which are connected through the Intel PCH. I tried disabling the LAN and USB 3.0 ports to free up resources but it didn't make a difference. Now that I think about it, I didn't try disabling the x16 port in device manager. I can try that, but I doubt it will do anything.
EDIT: Disabled the x16 port. No luck.
Another thing; this is the first time I've messed with a desktop GPU in over 10 years. The last card I owned was Radeon 9600. I stumbled upon the subject of UEFI and GPU compatibility. My laptop was one of the very last from HP before they switched to UEFI (bought late 2011). Is this the root of my problem?