Hello,First thing to check is your versions of Lilu and WEG to see if they are current.
If they are up to date then try boot argument: agdpmod=pikera
If you bought a used card that had the BIOS flashed for bitcoin mining that's a completely different issue.
If you are using MacPro 5,1 or older try the newer 6,1 from 2013 instead. The 2013 MP has dual AMD FirePro graphics cards so that is probably the better fit.The computer behaves like an original MacPro with a PC graphics card. No boot screen.
It works but you won't get the CPU PM to work as well as it does with MP 6,1.would iMac15,1 work as that is what i have chosen??!?!
MP 6,1 is still the best fit as it's also Ivy Bridge EP based. 15,1 is a Haswell Refresh iMac. The i7-3770 and the i5-3475S are consumer desktop Ivy Bridge CPUs from the same family as the IB EP processors. The only significant differences with IB EP chips in the MP is that they go up to 12 cores instead of 4 and they support ECC memory.I got CPU PM to work so its fine....