I don't think so. I've noticed that when the computer starts it gets very noisy, but when Cool'n Quiet gets in (the speed drops to 1Ghz, I think), there is a lot of less noise. So I'm thinking that the main noise comes from the processor fan.
I've bought a boxed Athon64. I think that if in the next 2-3 weeks I find it annoying, I'll replace the processor fan provided by BIostar with the one included in the processor box. Then I'll be able to tell you for real if the problem is in the case or in the processor fan.
Perhaps you can tell me how can I know if the noise comes from the processor fan or the case fan... The processor fan lies in the front of the case, while the case fan are on the rear.
And thanks for your comment!