[IMAGE] 6-pin connector on that PSU can supply current up to 11A, for +12V it's: 12V x 11A=132WSingle 18AWG short wire (<1M) can safely handle up to 10A (14A for solid copper wire)even more for 16 AWG (not sure what they're using for this PSU)although I would provision it down to say 6A due various reasons including connector quality (mechanical, galvanic contacts/oxidation) and to keep temps in a safe range (soldering, melting incl. plastic, catching fire).6-pin connector you have has x3 of those 6A channels (6Ax3x12V=216W)Your PSU is already putting maximum power limit on this rail to 132W.Safe ATX standard defines/restricts 6-pin connectors in a much safer range of 75W (lowest denominator so far if compared to PSU limit and safe 3x wires limit), but for 8pin connectors to 150W as was already pointed out by [NAME] de Oro  below.Since card is capped to 120W (with temp peaks going a bit higher) by manufacturer (and part of Wattage comes via PCIe 75W standard) - it seems like you're safe.
I bought a Dell OEM 365W power supply unit (D365EM-00) to replace the OEM 290W PSU in my OptiPlex 7020 with i5-4590. Compared to the 290W PSU, the D365EM-00 comes with an additional 6-pin PCIe connector, which I will use to power a "new" GPU card (140W max power draw by EVGA, 120W TDP by TechPowerUp). A 6-pin to 8-pin adapter will be used. My question is how many watts can the 6-pin connector of the D365EM-00 supply? I assume the GPU will get 75W from the PCIe slot in the mother board and will thus need only 65W more, and typically less since the GPU will not be used for gaming. The GPU is an EVGA GeForce GTX 1660 Ti SC Ultra Gaming, 6GB GDDR6, Dual Fan (06G-P4-1667-KR).
Power of 6-pin connector of OEM 365W PSU D365EM-00?