My edit machine is slower in processor speed than yours and my render speed is quite manageable. First thing is to try one of the online processor speed tests that check how fast your machine works. I'd guess that your drive isn't using its full speed, I did this on a previous computer when I simply put it on the wrong Sata socket on the motherboard. How many monitors are you running? Have you tried the on board monitor and disabling the video card to see if the performance suffers which it should. Check the drivers of the nvidea card and have you double checked the card is on the approved list?
