Okay, I know that the build of 10.6.4 is different on the 2010 models, if you run the old 10.6.4 build from the 2009 Mac Pro on a 2010, and then run Geekbench on the 2010 model, it only reports HALF performance across the board. You must run the proper build of 10.6.4 to get full performance from your machine. So my question is -- do you know if this would be an issue swapping drives from a 2009 Mac Pro to a 2010 running 10.6.5 on the drive? Is there an OS performance hit running the 10.6.5 from the 2009's drive on the 2010 Mac Pro? The reason I ask is because I am upgrading to a 3.33GHz 6-core, it's ordered and on the way. When it comes, I would just like to swap my SSD from my 2009 to the 2010 (running 10.6.5) and hope that everything runs OK. I don't want to have to re-install the new OS X build from the system disks and then update it, I would like it just to work correctly on the new Mac Pro. If you run the last build of 10.6.4 (public build) on a 2010 Mac Pro, and then run Geekbench, you will only get HALF the score you should. Roman23 tried this. He was getting like 5200 instead of the 11500 that he should have gotten with bhis W3580. He had to update his machine using the 10.6.4 disc supplied from Apple for the 2010 Mac Pro, it was a different newer build of 10.6.4 (not public release) that some kind of updated drivers for the Mac Pro 2010 machine. After updating, he was getting 11500 scores in Geekbench again with his W3580 chip on the 2010 board. I just wonder if these drivers are included in the 10.6.5 build which is installed on any machine. Any help would be appreciated. Thanks!