Need to clarify some things:

besides the Y adapter from 8pin to 2 6+2 pins that caused the meltdown I did not use any other adapters only what came with the PSUs. After damage I only use what came with the PSUs. The risers are MOLEX powered and to be on the safe side it is now 1 cable exclusive to one riser, MOLEX connector from the PSUs.

All PSUs are from corsair, I have read in their forums they use AWG16 from the first cable. I found on their forums one of the usual pigtail cables are specified up to 300W.
Right now Im testing the following:

- Reset all GPUs to factory settings
- Measure temps on the connectors with infrared tool

So I found this german article about stressing the NVIDIA 12 Pin connector: https://www.igorslab.de/tester-in-gefahr-wieviel-watt-ueberlebt-der12-pin-connector-der-nvidia-geforce-rtx-3080-und-rtx-3090-ohne-zu-schmelzen/

I find the following info useful:

- Temps are rising pretty fast within 10 minutes
- up to 144°C and connectors start smelling but not melting already

So far im mining for 25 Minutes and the hottest connector I can measure is the ones from the 1080ti and the 3070 around 52°C. I thought the connectors on the PSU sides are the hottest since this was where my meltdown occured. But these are cool @ around 35°C.

Lets assume one pigtail cable can make up to 300W before it starts melting. The TDP of 3080 is 320W. That would explain how it happened but is it really like 20W above specification can lead to temperatures in the 3 digit area? Is it like once you go above the specification it only gets warmer continously?