The SG05 case is available with two PSU options:
- 300W at 80 Plus efficiency
- 450W at 80 Plus Bronze efficiency

My plan is to stay very far from those levels, most likely around 100W or so.

Given that both are overkill, which PSU would for normal operation be preferred (less noisy)?

- Does higher efficiency translate to less noise for small loads?
- Is a less powerful PSU likely to be less noisy, for the same load?
- Would the more powerful PSU have more cooling, possibly producing more noise?

Thanks,

Fredrik

The heat output of the PSU will be a function of it's efficiency. If you can find the efficiency curves for each PSU from 80plus testing then look at the efficiency at 100W. Look for the waste heat percentage (eg. 100%-80% = 20%) and this would tell you that for 100W of output, 25W would be waste heat. This is the amount of heat that the PSUs fan needs to clear. In addition the more powerful PSU may have a higher rated fan (if it doesn't spin down) to allow it to clear more heat at 450W than at the 300W of the lower rated model. You can still replace the fan on each and this may be beneficial.