Hello i recently purched a 2008 mac pro 1.1 i have installed elcapitan and the new boot.efi using my 2011 imac. I have also installed a gtx 750 but my problem is it enters a boot loop and the gpu diagnostic light does not light up the original gpu works i have also tried to install a couple different pc cards and the same thing happens. I have installed the nvidia web drivers and when i boot with the gt 7300 and the 750 the system profiler and nvida web control panel see the 750 but it will not dispaly anything.