Short PCI-E 16x Risers work but Long ones don't?

[joshv06]

So I have some risers for my R9 290 video cards. The long ones are finicky. Some work in some ports. But the short risers work all the time.

If I mod them to make them powered risers, should I be good to go?

Thanks

[vm1990]

it should work but it could be the long ones are cheap and not carrying the signal well enough over the distance

[DrG]

How many ribbons strands per pin?  Cheap risers only have 2, the better ones have 3.