I am throwing around the idea of getting an older Mac Pro with the intention of throwing in a lot of upgrades myself. More RAM, SSD's, etc. I'm just curious which model/processor would be the best to get to offer a good amount of upgrade options. Basically, I'm just looking for a model that will still run decently with everything that can't be upgraded - so basically the processor. The 2010's can be had for a decent price on eBay, but I'm a little wary of anything before that. Any input would be great thanks.