As I already said I have RX 580, RX 570 and 3 5700 XT (14 GPUs in total). All cards running on risers 006c. All of the GPUs running fine except the 3 5700 XT which have random glitches. Changed everything: cables, risers (but always 006c), PSUs nothing worked. Do you think this is an opinion or a fact?
There is nothing that even remotely suggests the problem is the model of riser.
That's called jumping to conslusions and makes problem solving more difficult.
Instead of saying you've done "everything" how about listing the things you've tried, in detail,
without bias.
Have you tried the 5700XTs in different slots? x16 slot without riser? different rig?
Probably not because you already bought the new risers with the pretty LED and you just
want confirmation to make you feel better. If so fine, the LED will fix everything.