Hi all, I'm looking into upgrading my 2011 iMac (27" i5) and am debating buying a Mac pro off eBay. There are lots of 4,1 models that have been upgraded to 5,1 and have twelve core CPUs. This is quite attractive for me because I do a lot of numerical computing so being able to use 12 cores would give me a significant speed up. I also have access to a cluster but it's always nice to make sure everything is working locally before submitting a big job. These machines seem to be around $2k, do you all think they are worth it? I'm slightly worried about buying out an older machine. I know they don't have thunderbolt so I can't use my imac as a screen which is a shame. Any advice/alternative suggestions would be much appreciated!