The fan has not been upgraded, at least from what I read in the product webpage. It mentions going from standard 80mm to 92mm but the Gold version already uses 92mm fan. No mention of an improved fan speed profile.
The 3 'major' upgrades are 'From Gold to Platinum' and paracord individually sleeved cables and the ATX bracket.
Hmmm, I remember Corsair rep here once said that changing to such a set of upgraded cables would increase the cost of the PSU so much that Corsair will not do it. But now, it is done! The price increase is only from US$120 to US$140.
The fan is 92mm as on the gold version had too. However it is now a PWM-fan and the fan-controller has also changed to a programmed MCU that takes both temperature and load into consideration, as well as a delay.
@Corsair Johan Any information to share regarding the status of the SF600 Plat?
No information about that yet.