Now the GPU manufacteurs learnt their lesson and over-supplied the market but the motherboard manufacteurs didn't and hashrate is capping because motherboards are sold out.
plenty of good motherboards if you don't mind 4 card or 5 card rigs.
The over supply of GPU's sure didn't last long, they have been out of stock everywhere for about 2 weeks now. June should bring new supply BUT everyone is so hungry to buy more they will be gone extremely fast then you gotta wait until july.
You can still swoop in on Nvidia gpu's though.
Honestly I like building 4 card rigs, I have a older mobo that I can get used and it is cheap + reliable. It seems there are a lot of issues once you dive into 6 card rigs getting them to work and that is before you deal with functioning risers.