From Amazon
Noctua NF-A4x20 5V, Premium Quiet Fan, 3-Pin, 5V Version (40x20mm, Brown)
CCL Computers AMD
Noctua NF-A4x20 5V 40mm Chipset Fan
3DJake
Noctua Fan 5V NF-A4x20 - 3-Pin
Conrad Electronic
Noctua NF-A4x20 5V PC fan Black (W x H x D) 40 x 40 x 20 mm