Please provide CPU model, mobo model, GPU model, and case model.
1) I don't recall for sure, but I have to assume the Intel HSF will do less than 1100RPM. The Intel stock HSF is tuned for low noise at the expense of higher thermals
. Unfortunately, it sounds like idle noise level is bothering the owner. There may not be much improvement to be had in regards to an aftermarket cooler.
2) Fan controllers or resistors are helpful for case fans, but probably not the best idea for a CPU fan for reasons MadManOriginal
outlined. Are you sure the problem isn't a noisy case fan/s?
3) Install sound dampening foam like this.
4) Buy a case that is built for silence. Something like the Fractal Define R4
or NZXT H2.
5) GPUs are a bit trickier, you can always use an aftermarket cooler like Arctic Cooling offers, but they're oftentimes expensive. Depending on what GPU is being used, you may (unfortunately) be better off buying a different GPU that's quieter. Asus' Direct CUII coolers are some of the best on the market IMO, or you might be able to find a passively cooled model.
Main: i5-3570K, ASRock Z77 Pro4-M, Asus GTX660 TOP, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Hand-Built Wood Case