First of all thanks to tiamo for breathing new life into the old warhorse. I have the 1,1 running mavericks and even installed a Gtx660. While it is definitely faster than my 4870, it seems not as fast as it should be. My iMac with 775m seems smoother. I have heard a few different things on the PCI bottleneck with some people saying it should not be a bottleneck yet but others have said there is really no benefit from running anything like a 660 on a 1,1 as performance will be bottle necked. Any thoughts on this?