Yes.  The chipset only support 4 PCIe 1x slots off the socket - it delegates any more to the northbridge, which may behave differently/slower possibly?

see the chipset diagram http://cdn.overclock.net/f/f3/f30d12f6_AMD_A85X.jpeg
from
http://www.overclock.net/t/1459052/amd-a10-7850-preview-by-flank3r