Hi, I'm using Elsa GTX680 S.A.C 2GB graphic card in my MacPro3,1 @3.2GHz. I bought the card as "over clocked" at an auction and it's working great with the Apple logo showing up at startup. Lately I realised, however, that the startup manager is not working and I'm unable to select a startup volume, safe boot or clear PRAM when booting. I'm wondering if this is the way a flashed graphic card behaves. I want to clear PRAM to see how this will change but, since I cannot execute such a basic command with my Mac Pro, I'm stuck wondering if there is a way around. I boot the machine from either an SSD attached to the Sonnet Tempo SSD Pro Plus and configured with SoftRAID at RAID 0, an external SSD via eSATA 5G connection to Caldigit FASTA-6GU3 Pro, or an internal HDD on Mac Pro RAID in JBOD. I had no problem like this before customising my machine in this setup. The Startup Disk in System Preference is working and selecting a different volume is no problem there but the Startup Manager remains dormant when I start my Mac from any of three startup volumes and, guessing from the black screen issue of the unflashed PC graphic cards, I suspect my GTX680 is the cause. Can anyone help me on this? Thanks.