My 2008 Mac Pro has been rock stable since 10.9.2 (before that, just the 'mail, are you drunk?' issues). Sounds a lot like the problem is graphics switching -

My 2008 Mac Pro has been rock stable since 10.9.2 (before that, just the 'mail, are you drunk?' issues). Sounds a lot like the problem is graphics switching - everyone with issues here has two graphics adapters.