I have a problem with hoarding PC parts. 5-10 years ago, computers didn't evolve as quickly as it does now, so owning a few Pentium 2/3/4's wasn't such a bad thing.
Since Intel started selling their Core i3/5/7 processors, I've finally decided that all my old computers are obsolete. A few years back, I replaced 2 P2/P3 servers and 2 P4 PCs with an i7. In a month or so, I'm probably replacing my P3 router with my last P4. I might save some drive cables for cheap board-to-board interconnects, but besides that, everything else is going in the trash, er, I mean recycling.