I have a 5,1 which currently has the x5650 stock configuration. This machine is my general desktop, plex server, what little photo editing I do, as well as, some Xcode work. I do not use photoshop (not that creative), but will be doing some iMovie. I have an SSD boot, a R9-280X video card, and a USB3.0 card. I am looking to do the CPU's next, because they are next on the hit parade of things I want to do with this machine. I also have a second 5,1 with the same CPU configuration that I am currently leaving stock (which is the family iTunes server, my wife's photo backup, and a place for me to stash hard drives for storage). Anyway, what I am looking at is adding some pep to my desktop experience, though I admit, the performance is pretty good generally, I would like a little faster user response. I picked these chips, because depending the days of the week, they are all can all be had in the $100-$150 range for a pair on eBay, a little less for the 5677 and a little more for the 5679. I guess specifically I am looking at the tradeoff between clock speed and cores?