More Fans = Quieter Build?

I'll start this off by talking about me and my friend's build, as relevant to our cooling/noise as I can...

As for my rig, I have the CoolerMaster 690 II Advanced with the three stock fans (two 140mm and a 120mm). A CPU cooler with a 120mm fan and a Palit JetStream 660 ti (two 80mm fans I believe).

My friend, with the CoolerMaster Storm Trooper case with about six fans, varying from 200mm to 120mm. He also has a Gigabyte 770 factory OCd with 6GB of VRAM and the Deepcool Gamer Storm Assassin cooler with it's two stock 120mm & 140mm fans. He also has an extra hard drive than me, one a WD Black and the other Green.

His PC runs A LOT quieter than mine and maintains lower temperatures, not much, but it's lower.

I have all my fans running between 30% - 40% any lower and it would make me feel uncomfortable with my cooling, the GPU is set to 30% minimum on idle, something I cannot change and don't particularly mind.

Sure, the noise isn't too bad, it's completely fine with me really. It's just I could potentially shush my rig a bit by adding/switching the fans (I would go for Noctua, of course).

Can anyone answer my shortened question; can more fans, running at lower speeds, maintain the same temps as a rig with half an many fans and be quieter at the same time?

Thanks in advance for any input.

Bigger Fans that are running on lower RPM will be quiter than small fans that have to run at a higher rpm to move the same amount of air so if you throw a couple big low rpm fans in it will be likeley less  noisy while maintaining the temps you currently have

For what you want, I believe premium quality fans are the way to go.  You mentioned Noctua, they are some of the best. You may also want to look for a fan controller.  This will most certainly quiet your PC; however, it's unknown as to what sort of temps you can expect.  I doubt there will be much deviation in your current temps.  They may improve by a degree or two.  It certainly won't be anything major.

+1  I was thinking the same thing.  Unfortunately, the largest fans his case supports are 140mm

Mmm, okay, thanks again.

I suppose that neither of you would know? :| It would help a lot, maybe I'll buy them anyway and make a fresh topic later showing my results.

if you can fit twice as many fans as you currently have into your system and then let them run at a lower rpm (not necessarily half the stock rpm) you should get simillar temperatures and less or lower pitched noise