- The system won't pull more than 350 to 400W - A GTX 1080 needs less power than the R9-280X -- AnandTech and others have shown that - System Idle is around 80W (thanks AMD ^^) -- 20% load would be around twice: ~150W. So the PSU runs at about 10% load in idle --- When running at 10% load the PSU has a worse efficiency - Why the fuck is he buying a AMD GPU? Ahh.. Hackintosh BS :/ ("no real NV drivers...") - Even if OCd, the system will not pull more than 400W (look at AT and their OCd X99 system). Maybe 420W.