Will a x1 to x16 riser work on a pcie x4 slot?

hi guys, i have one gigabyte motherboard, ga ex58 ud3r.

it has 2 pcie x1, 2 pcie x16 (crossfire) and 1 pcie x4.

i was wondering if i can use 5 gpus in there or only 4

so the question is as the title? can i use a x1 to x16 riser on a pcie x4 slot? have anyone tried this and does this work?

thanks