Do I need a better PC?

ok, sometimes when I run my Ethercat servos, they sound like they have bad bearings/run rough. Restarting linuxcnc sometimes solves it and they run buttery smooth. I've also gotten a warning unexpected realtime delay. Im guessing Its because Im running the cheapest HP pavilion desktop junk(runs off a little wall wart and has the smallest cooling fan on a 1x1" cpu heat sink. ) 
Anything I should look for when buying a proper motherboard for ethercat linuxcnc?

I don't think its a servo hardware issue. All of them sound like gravel sometimes. Or they are all smooth. I'm wondering if its something to do with the feedback loop between the servo and linuxcnc? It sounds like they are being commanded unsteady changing speeds at a somewhat high frequency. They only have UVW coming out of the motor. And encoder seems to have standard a/b v+ v- stuff going on. I don't think there's any hall sensor for the rotor.