18 AWG vs 16 AWG

[RxFX]

I can never really find an answer online as everyone has a different view and experience of this . Some power supplies (most actually) come with pigtail pcie connectors and some say it’s ok to use the pigtail to power like a 16 pin gpu (multiple connectors needed basically) some say you can’t . Most accurate thing I’ve heard is that an 18 AWG cable can use the pigtail due to the power draw and 16 AWG can’t (idek what those are btw) . So how do you know if your pcie cable from your psu are 18 or 16 I tried searching for mine but idk how to know . Msi Mag A650 BN psu btw

 

[VashHT]

Sounds backwards to me, 16 AWG is larger so it has more current carrying capacity than 18. AWG is the wire gauge, lower AWG is a larger wire. I quickly looked up a couple manuals from power supplies and they don't seem to list the AWG but tbh I don't think it matters. I'm running a 3080ti with pigtail connectors, honestly I don't think I've ever not seen a pigtail connector for the PCIe power.

 

[William Gaatjes]

Sounds backwards to me, 16 AWG is larger so it has more current carrying capacity than 18. AWG is the wire gauge, lower AWG is a larger wire. I quickly looked up a couple manuals from power supplies and they don't seem to list the AWG but tbh I don't think it matters. I'm running a 3080ti with pigtail connectors, honestly I don't think I've ever not seen a pigtail connector for the PCIe power.

I never heard of pigtail connectors. I just noticed it is a generic description of crimped wire connectors with multiple connections. Graphic cards use PCIe power connectors. And there is some variety to be found over the years.

I can never really find an answer online as everyone has a different view and experience of this . Some power supplies (most actually) come with pigtail pcie connectors and some say it’s ok to use the pigtail to power like a 16 pin gpu (multiple connectors needed basically) some say you can’t . Most accurate thing I’ve heard is that an 18 AWG cable can use the pigtail due to the power draw and 16 AWG can’t (idek what those are btw) . So how do you know if your pcie cable from your psu are 18 or 16 I tried searching for mine but idk how to know . Msi Mag A650 BN psu btw

If it is a powersupply from a proper brand, you can be pretty sure that the wire gauge is sufficient.
The wire gauge is at least chosen based on the current capacity of the pin of the connector the wire is connected to.
The connectors with pins are chosen according to the then known power draw that is to be expected. SInce the voltage is +12V, that means that the current draw can be predicted within a safe margin. : P = U * I ; P = power, U = voltage = 12, i = current.
For example, if the pin is able to handle 1 Amp of current, then it is useless to use AWG16 which from the top of my head can handle 10 Amp easily. Why ? Well, the wire can handle that current but the pins will start to heat up and may even start to burn.

This has to do with (electrical) contact resistance, the size of the pin. The crimping quality, how the wire is joined to the pin. Material composition of the pin and contact surface plating. If it is a friction connector or that there is really a small cut made into the pin during connection with the opposite part (Male - Female connections these are commonly called).

Vibration resistance is also an element of connector choice but for a stationary placed desktop system not really an issue, however if you take your system to lan parties, you should be careful how you transport your delicate system.
Although the connectors are chosen to be able to handle vibration, i am pretty sure that these connectors are not automotive connectors that can tolerate massive amounts of physical vibration , think driving in a car on a bad road.
And besides connectors, think about aftermarket cooler on the cpu that weighs al lot and put a large strain on the motherboard if you move the desktop system around al the time in a car.
Or a really heavy graphics card that cost more than a thousand dollars or euros. The sheer mass reduces the tolerance for physical vibration of a desktop system.
Physical vibrations which can cause cracks in electrical components like for example ceramic capacitors or resistors.
The ceramic capacitors are mostly used to stabilize the powersupply to for example the cpu. Think droop and voltage undershoot, voltage overshoot. But also to reduce EMC electromagnetic interference caused by current draw spikes(Think cpu cores ramping up and ramping down in clock speed because of required calculation load) .

These kind of scenario's where there is unnoticed damage, are often the reason a system becomes unreliable and can be the reason for blue screens with windows or system crashes, or linux system crashes or hang ups. Assuming there is no way overclocking happening here. That is another story.
So, be gentle to your system when you transport it. Wrap it in pillows for all i care when driving the system around. I know i would and i do not even have such an expensive system.

Anyway...
Also, the pins are designed for a certain current and therefore also designed to be used with a specific wire gauge in a very narrow range. Sometimes even just one wire gauge is allowed according to manufacturer specifications.
Often molex connectors are used , sometimes with a unique keying. Keying means that the connector is not interchangable with other more generic molex connctors or molex compatible connectors from other brands like for example Würth Elektronik.
But if the keying is compatible with generic molex connectors, then the keying is of course not an issue.

Long story short. you better make sure that the PCIe power connectors from the power supply fit properly in the graphic card. Because that is what is not fixed to one model connector.
Over the years several types of PCIe power connectors have been introduced to handle the power draw of graphics cards. Like 6 pin and 8 pin.

Sometimes there are cheap adapters available and there you should be very cautious before you buy for example a cheap PCIe power connector adapter. Because sometimes the specifications of the manufacturer of the PCIe connector are not followed. And thay can be a recipe for a very expensive disaster.