Pretty much like I thought. But thumbs up for a good explanation. To the discussion on quality of risers - the problem with risers melting. Is this due to internal current/data transfer in the cables, or from heat from GPUs?
The melting of riser can be for various listed reasons.
1) The power type of the riser and the power flow.
i.e, A SATA string can handle up to 54 watts of power safely on one point of connection. A SATA string in total can draw up to 110 watts of power from PSU safely. So, If I use a SATA string to connect two risers with GTX1060 GPUs on them which draw around 35-40 watts of power from the riser, totalling to 70-80 watts. I'm fine using SATA connection for my riser in long run.
Another scenario, I use a single SATA string to connect two 1080ti, which consume a little over 65 watts each. I'm just waiting for fireworks in my rig in long run. I'll have to turn over to MOLEX which can handle up to 70 watts at one point of connection and can draw around 154 watts from PSU. So, a MOLEX strand to power two 1080tis with the riser. Moreover, six pin risers are the best possible solution out there but hard to come by.
2) Quality of risers.
i.e, There is no way to check the quality of risers that I know of, but I have a box of black coloured and blue coloured risers. I prefer the black ones. They are more sturdy in feel. All the risers that I've used, I'll recommend not using that cheap SATA to MOLEX convert that comes with the pack. They are the worst of all and the main reason of melting. On further inspection, I saw they were made of Aluminium which is not the best metal for electrical conductivity.
3) Wrong placement of x1 adapter in motherboard.
i.e, I've seen many first timers plugging the x1 adapter in wrong place on their motherboard which resulted in instant failure and damaging of motherboard or GPU. Don't ever make that kind of mistake and always double check before starting your system.
Friendly advice, don't go into mining if you can't afford 6 GPUs. If you start with 2-3 and plan to upgrade with profits, it will take much more time and it won't be as profitable. Most people don't take into account that mining profits with certain GPU fall over time.
Pretty well said!