Quiet 50mm case fan w/ 2 pin connector?

Question

I have a watchguard firebox firewall, which works great, but the fans in it are incredibly noisy.  The fans are Sunon 50mm X 50mm X 15mm fans (KDE0505PHB2 is the model number)  They have a 2 pin mobo connector, not the usual 3 or 4 pin. Does anyone know where I can get some (much) quieter replacement fans?  The 2 pin connector seems to be the sticking point.   Thanks. --kurt