I know there has been much discussion on this general subject, but I am looking for specific opinions for my recently upgraded 2009 4,1 MP 8-core 2.93ghz (from 8-core 2,26). It runs great except it goes into deep hibernation and won't wake up if i put it to sleep either from the apple menu or from the system preferences. (The problem started after the CPU's were upgraded) The fans were going crazy and apparently SMC got completely corrupted for some reason. It's already been to the Apple repair place and they reflashed the Boot ROM Version: MP41.0081.B8. Now it runs great but doesn't sleep properly. Getting tired of monkeying with it at this point. All the drives/ram & video card are new. Ran an 2 and 8 hour Diglloyd memory/CPU stress test and ran some pretty hairy photoshop tests with 15Gb files and it never broke a sweat, got hot or crashed. Specs: Previously mentioned processor upgrade New ATI 5870 card 96GB 1066Mhz OWC ram Boot drive: 480GB 6G SSD PCIe: Two Accelesior 480GB SSD cards HD's: Three 4TB Black Caviar drives So here's the specific scenarios I'm looking for answers to... (And I don't care about electricity usage, just what's best for the machine)... I'm leaning toward leaving it on all the time and just putting the monitors to sleep. (perhaps a shutdown every couple weeks so it can reset) Or is shutting down nightly better? (Concerned about the stress on PS and and temp fluctuations on components from daily powering on/off.) What do you guys think?