Then your PSU has come incomplete somehow, is it second hand or brand new?
Both PSUs pictured in this thread, are of your exact PSU model, and it clearly shows two 4+4-pin cables (they are both 8-pins on the PSU end, and 4+4-pin on the CPU end)
EDIT :
Take a clear photo of ALL cables for your PSU and arrange similar ones side by side. Upload the picture and link to it here - I'll try, or someone alse will, and point to the right cables in you picture. Make sure all cables are there, and they are sorted properly