is it safe to use 2 molex pins to power an rx580 8gb?

[XDXDD]

so for context i guess is that i have a ryzen 3 3200g and I've researching about stuff and came across a RX580 and those gpu's are decently priced used, the main issue is i don't really have the necessary pin to power it but i have 2 molex pin laying around my pc, i searched that there's an adapter for it so that i can turn into a 6 or 8 pin, so will it be safe and compatible? will i be able to "overclock" it? thanks! i'm quite new here so i don't know what to do and i don't have enough budget to buy a new psu that have necessary pins.

[Needfuldoer]

What are the rest of your system specs, and what's your budget?

 

If you don't have PCIe power connectors available, your power supply might not be powerful enough to run a dedicated GPU.

[tkitch]

What model and wattage is your PSU?

You can expect a RX 580 to hit 150ish watts at full tilt, so you need to make sure your PSU can handle that.

[mariushm]

A RX 580 consumes  up to around 225 watts for the 8 GB version.  It will take around 70 watts from the slot, and needs to take almost the full 150 watts through the pci-e 8 pin connector.

 

You can play with the power settings in the AMD control center to reduce the video card's power consumption by 20-30 watts but still a cheap adapter cable would be somewhat unsafe.

 

A 2 x molex to  8 pin connector is safe up to around 100-120 watts, if you connect each molex to a separate chain of molex connectors.  The individual molex connectors have a maximum rating of 5A per voltage, so it can do maximum 60 watts per connector.  SATA connectors are worse at around 4.5A per voltage (but honestly I wouldn't use them for more than 3A)

 

It's important for the power supply to be able to provide enough power on 12v, look on the label of the power supply and see how much power it can give on 12v - you'll have a value in A (that's current), you can multiply with 12v to get the watts. For a RX 580 you would want at least 300 watts to be available on 12v for the computer, it depends on what CPU and how many hard drives and fans you have.  A CPU will consume around 50-100w from 12v and each hard drive consumes around 5w from 12v, and each fan consumes around 1-2 watts from 12v.

 

 

[--SID--]

What's the brand and model of the PSU?

 

Usually molex cables have 20AWG wires. Those wires are rated for 5A. On a 12v wires that's 60w. Since a molex cable has one 12v wire it is able to deliver 60w, no matter how many molex connectors are on the cable.

[mariushm]

Eh the actual cable is often AWG18, which can do 9-10A easily...  but it's irrelevant ... the ratings are conservative to account for situations where you have a bunch of cables bundled together with no space for natural air cooling. 

 

The wires themselves can carry even 10A of current, they'll just warm up a bit more, and the insulation on the wires could be affected. Cheap ass cables will have insulation that's only good up to around 65C .. good cables and adapters will have insulation that's good for 85c and higher. With 10A or so though a small length of cable, the wire will heat up maybe 20-25 degrees above ambient, or in other words, the cable will be warm, up to around maybe 40-50 degrees Celsius. 

 

The problem is rarely the wires, it's often the actual pins / contacts inside the molex connector, those are rated for around 5A, which can become looser due to constant heating and cooling. As they become looser, there's higher contact resistance at the connection and you get more heat there, which can melt the actual plastic of the molex connectors. 

 

SATA connectors are worse, the cheap molded connectors have plastic that will soften and deform with high temperature, hence why I never used molded sata connectors. I also don't trust them for more than 3A of current, no matter what kind of sata plug / connector i deal with.