GTX 1070 OC question

[CloudbaseJ]

Hello
Is it normal that an overclock is less stable when using risers instead of direct into pcie slots on mobo?

I was getting 33mhs at +950 memory and 60% power when my cards were in the mother board but now I'm using risers I'm only getting stable results at +750 memory.

This is the same cards taken from my gaming pc and put into a mining rig.

Also is it worth a core OC for dual eth/lbry?

Cheers