Hi. I recommend the Gentle Typhoon 800rpm@12v but they only come in 120mm i guess.
Actually, if I was going to *replace* the fans, I would get a PWM fan... my mobo's CPU fan headers can only vary the PWM signal, not the voltage (unlike my chassis fan headers, which can vary either).
Unless the GTs are up to efficiently cooling a 3770K @ 4.2 GHz at load?
But it's all moot anyway; I'm not buying the PH-TC14PE at $90 if the fans it ships with aren't good for horizontal usage. If I am buying my own CPU fans, I'll just get a Prolimatech Super Mega or something similar and call it a day.