Backstory:
Hi, 1+ year ago I wanted to have a more modern power-supply with PCI-express power cables (360 watt Chieftec Dragon case PSU before) and I checked reviews including CoolerMaster V700 and the EVGA SuperNova G2 750 and a lot of others and preferably on JonnyGuru.

I settled on the G2 750 because of electrical quality/results and that the fan could stop completely.
However I've read on the site that he don't think doing so is a good idea so I always have it on anyway.

The CoolerMaster PSUs would have a LDB fan instead and by now Corsair RMx exist among the competition (and SeaSonic has always done but at a higher price-point, same with AX and so on.)

Anyway, I help people pick components and suggest products on a freedom of speech board (Flashback) here in Sweden and as such when some guy had picked some 80 plus Bronze BeQuiet product I suggested the V650, the G2 650 or the RM650x instead and listed the differences I knew within the three and eventually he changed PSU to the G2 650 which he has ordered.

The problem and question:
In the process I mentioned that I had the G2 750 which it seem like he took as an advice to get that which it wasn't and he then made the claim that supposedly the fans of the 650 and 750 was different and the 650 made less noise.

I wanted to find out where that had been said and found it on Techpowerup and also made these comparison charts:
As can be seen from those two in their test the G2 750 was 5-9 degree hotter at low load but just 3 degrees colder at a high load while at the same time being almost 10 dB noisier at around half load and being noisier for all the time the fan is on.
 
That's rather disappointing. I don't have a new machine and while this one make much less noise than my even older one it make quite a bit of noise and the PSU at these loads don't make more noise than the rest of the machine. However I think the extra 10 dB of noise is a problem, especially when also coupled with higher temperatures.

There are different fans and this temperature difference is real and is there between these (650 and 750 watt G2) two models?
Why isn't the fan of the G2 650 used on the G2 750 too? I already hold the 180 mm of length/depth of the G2 750 against it because it make it unsuitable for many micro-ATX cases. I don't know if there's a fan-size difference but if there is obviously the G2 750 fan isn't better (maybe it is for more powerful units where it can spin quicker than the one in the less powerful models.) I don't remember if the G2 750 previously was the smallest model and if G2 550(?) and 650 was new models added to the range and if the component change is an improvement of those, one which haven't made it into the older models (or maybe it have but hadn't done so in the test Techpowerup did?)

Anyway - it's so disappointing, I don't want a hotter PSU and I definitely don't want a much noisier one than necessary! So sad 

Images from Techpowerup, rescaled and transparent to make them line up.