ITX Build, Budget GBP 1,200 - Can you do better?

[bowrilla]

15 minutes ago, brob said:

Never understood this argument. The efficiency difference between 50% load and 67% load is quite small. So it seems to me that for any given load, the difference in thermal waste will be quite small leading to very similar fan speeds.

While you are correct with a slight difference of only a few percent in efficiency, you're wrong concerning noise. They have different fan curves and the more powerful psu uses different components. The Corsair SF450 for example produces about 24–25dB of fan noise at 360W of load while the SF600 will only produce about 20dB of fan noise. The SF450 is fanless up to ~90W of load while the SF600 runs fanless up to 120W of load. Bigger psu, more thermal reserves, different fan curve, lower noise level. 

Efficiency-wise you only gain about 2–3% … that is true.

[jeffery7466]

44 minutes ago, bowrilla said:

While you are correct with a slight difference of only a few percent in efficiency, you're wrong concerning noise. They have different fan curves and the more powerful psu uses different components. The Corsair SF450 for example produces about 24–25dB of fan noise at 360W of load while the SF600 will only produce about 20dB of fan noise. The SF450 is fanless up to ~90W of load while the SF600 runs fanless up to 120W of load. Bigger psu, more thermal reserves, different fan curve, lower noise level. 

Efficiency-wise you only gain about 2–3% … that is true.

That is true. But I don't think that I'll be annoyed by 25db. To me it doesn't justify spending 40quid more.