schwellmo92

You are flat out wrong dude. The only difference is the two new pins are grounds. Something to keep in mind is that the RX580 stock is rated for 185w so in theory it should only draw 110w from the cable and the other 75w from the PCI-E slot.
 
If OP is really concerned about the misinformation you guys are spreading he has a few options:
- if you have 2x molex spare on the PSU you can use 2x molex to 8 pin
- you can plug your 6 pin in to the 8 pin on your graphics card (it'll only go one way) and your card should automatically run at a lower power envelope
 
Anyways I'll add some proof to backup my claim that a 6-pin to 8-pin is fine below, the only exception would be is if your 6-pin cable use very thin wiring which is not common except for on extremely low tier and old PSU's.
 
http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress8
"The PCI Express 2.0 specification released in January 2007 added an 8 pin PCI Express power cable. It's just an 8 pin version of the 6 Pin PCI Express power cable. Both are primarily used to provide supplemental power to video cards. The older 6 pin version officially provides a maximum of 75 watts (although unofficially it can usually provide much more) whereas the new 8 pin version provides a maximum of 150 watts."
 
http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress
"Nonetheless, information leaks out from the specification and the 6 pin PCI Express power cable is actually rated at an extremely conservative 75 watts. I have no idea why the wattage is rated so low because the specifications from Molex clearly allow substantially more power."
 
"Nonetheless, the 6 pin PCI Express power cable officially provides only 75 watts. In all likelihood, however, real implementations of this power cable can provide far more than 75 watts."
 
https://graphicscardhub.com/graphics-card-pcie-power-connectors/
"If your graphics card requires an 8-pin connector but your power supply has only a 6-pin connector then you can use this 6-pin to 8-pin connector or adapter cable for powering your high-end graphics card."
 
https://www.gpuminingresources.com/p/psu-cables.html
^ these guys have a 2x circuit 6 pin at 216w max and 3x circuit 6 pin at 288w.

You can use a 6-pin to 8-pin adapter just fine. The 75w limit is just a standard, they both have the same amount of 12v pins therefore will both carry the same amount of power. The limit however might beat your PSU, if it has multiple rails it may not be able to push 150w to that 6-pin connection on the PSU. I just wouldn't push your luck by doing any overclocking or power limit raising.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

RTX 4080 12GB should really be the RTX 4070 but is called the 4080 so they can say the 4080 starts at $899 and make it look like prices haven’t gone up much. Change my mind.

12600K launched at $320 MSRP, what makes you think the 13600K with more cores will launch at a lower price? If anything the price should increase.

Used 3070 EVGA XC3 Ultra in Feb 2021 for $1020 AUD (730~ USD)

It is a 3080 “tier” membership. It doesn’t run on a 3080 and you don’t get your own dedicated GPU.

Graphics performance should be pretty close, the 5700G has a much higher power budget which is reflected in the difference in GPU clocks (1-1.6 vs 2ghz).