SPCR

My case (Fong Kai FK-320b) has one of those fan ducts that mounts to the rear 90mm vent. I've been following Fong Kai's recommended setup, which is to have the front 120mm and the rear 90mm both blowing air into the case. The noise produced by the rear 90mm with fan duct blowing cool air onto the Athlon 64 CPU w/ its own HSF blowing air onto the heatsink is too loud. So I was wondering if I could safely disable the fan on the CPU's heatsink and just use the rear 90mm fan and duct to cool the CPU?

Thanks in advance.

Just download Speedfan to monitor the temperatures and experiment away. As long as full load CPU temperature doesn't go over 55^C, you're safe.

To get your CPU to full load, use CPUBurn.

I think that IF you get confident enough in your experimenting to actually try turning the CPU fan off that you should remove the CPU fan all together, since at that point the thing will only block air blowing onto it. Good luck.