Picture the first half of a bell curve, and thats pretty much what a fan curve looks like, with the top setting of 100% fans at 70°C.
In quiet mode, it's a long, low rise curve with emphasis on keeping fan rpm lower. Temps under loads will be highest as a result.
In standard mode, the curve is a little more aggressive, so noise is reciprocal the the faster fan rpm. Temps are midline.
In performance mode, the curve is the most aggressive, fans will hit high rpm much faster, so temps are lowest.
On my nzxt x61 the difference between performance and silent was 6°C at 100% Prime95 loads, but the fan noise was double at any level. So I sacrificed that 6°C spread (it was 0° difference at idle, 6° at max or about 4°C gaming) for an almost silent pc. It was cool that I could get lower temps if I wanted to, but the cpu running at 51-52° or 55° in gaming loads makes exactly no diffetence to anything but a benchmark.
With coolers of that kind of ability, you have options, lower temps or lower noise or mix of both.