Suitable replacement fan for Stock Athlon 64 HS?

[SPOOKYSHOGUN]

I need to replace the fan on my OEM (Ajigo) Athlon64 HS but the 70mm fan that is on it is a Delta rated at 3050-6000 rpm and I'm not sure what CFM. Anyone know of a suitable replacement fan or where I could buy one? I can't seem to find a 70mm that goes up to 6000 rpm.