I managed to get my setup working. After failing with the BOXDQ67OWB3 last year, I ordered a MSI Z77A-GD65 at that time and I only recently managed to get around and test the GPU passthrough. And after setting the pciHole and msiEnabled= false, it worked.(CPU is Intel i7-2600 @ 3.4Ghz)
I'm curious to see if anyone with the BOXDQ67OWB3 who failed before is able to get it working with the msiEnabled= false solution. Don't forget to try different pcie slots.