Fans are great but USDT owners read on....
by LeeI also had a problem with an HP desktop, mine was an Elitedesk 800 but the USDT form factor means the only fans that will fit are 60mm. These are inherently noisy in such a small case compared to a standard size fan so I replaced them with these which are super quiet when outside the case. However, a word of warning, being 3 pin they spin at full speed all the time and a stock HP desktop like mine doesn't allow fan control via software or bios. Because the case is so small there's no way to get silent running with this size fan at 1600rpm when they're in position. My pc sits a foot away from me so is still far from quiet. I reduced noise further by adding noctua noise reducing cables to intake and exhaust fans, these lower voltage by approx 30% so both fans are now spinning at 1100 rpm and my pc noise is finally acceptable. This is still plenty to cool the pc too which is well overpowered for what I use it for. ( I5 4590, 16gb, Samsung SSD added )