http://www.alltronics.com/fans.htm has a 40mm 5vt assembly
http://2cooltek.safeshopper.com/69/cat69.htm?958 has 5vt 40mm
no idea if these will fit w/o modding.
http://www.mouser.com/catalog/618/1114.pdf for 5 and 12vt chipset coolers (caution high prices)
The fan is on a temp sensor and will only run when required, it cycles on and off by design. The first time I opened one, I thought the darn thing was dead. I pull them every so often to blow out the dust and lube the bushings. Just a thought.
You might want to check the OS version you are running, I have no problem with maxtors with ATA133 other than the snap runs pio and not ata it seems. Did you start with a freshly low level formatted drive? Curious...