Before ordering a fan you might try SpeedFan. Both the CPU and chipset chipset fans are controllable on the VNF4. Generally, cutting the fan speed drops the noise considerably with little or no change in temp. SpeedFan can be set to control the speed based on temp.
The VNF4 doesn't need much fan speed on the chipset unless you're overclocking so you can likely turn both fans down until they're inaudible. I have the older VNF4 without a chipset fan and have SpeedFan set so the CPU fan is inaudible; occasionally, the fan speeds up to audible under heavy load.