Question My pcie express is not providing enough power

Jan 17, 2021
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Hello guys, right now Im having a problem with my GPU ( GTX 960 2gb) power usage. The problem is that is not getting 75 watts from the pcie express on the motherboard, instead is getting more power from the 6 pin. This is a problem for me because im using a MOLEX to 6 pin power adapter and i dont want the thing to melt.



The TDP of the GTX 960 is 120 Watts, but in my testing never got over 110 Watts.
 

Math Geek

Champion
Ambassador
that's by design. pulling too much from the motherboard is not good at all. so most firmware shifts the bulk of the need to the 6/8 pin connections.

you're issue is not the mobo, it is the fact you need a psu that can power your system. those adapters are ALWAYS a terrible idea and can lead to frying parts or causing a fire depending on the moment it decides to finally go wrong.

do yourself a favor and get a psu that can actually power your system before you lose more than a 960!!

there is no way to "adjust" how the card gets its power. that is determined by the card's firmware and how the pcb is designed.


edit: other question would be how do you know how much power is coming from where? that's not exactly normal reported info?
 

InvalidError

Titan
Moderator
The PCIe slot only has a few tiny pins delivering power to the card, overloading them is not a good idea since it may fry the PCIe slot itself. That's why new-ish GPUs use auxiliary 12V power in the first place and should be used with a PSU that comes with PCIe AUX cables. If your PSU does not have any, then it likely shouldn't be used with 70+W GPUs.
 

DSzymborski

Polypheme
Moderator
If your family is being held hostage by a madman who is demanding you get a file off a computer with a power supply and there are no stores open, then you can use a molex to PCIE adapter. Or, you've accidentally set off a timer that explodes a nuclear bomb in a major population center and it can only be deactivated by a PC using a molex to PCIE adapter, you can do that, too.

All other situations, no. Buy a PSU that's properly suited to your specs. If you need an adapter, it's not.
 
I don't know how you got the idea that the pcie slot is not delivering power.
I don't know where that might get reported.

What is the make/model of your motherboard and psu?

A motherboard may have a optional 4/6/8 pin eps socket that the psu must fill to generate added power for heavy overclocking and pcie slot usage.
Is that filled?

If your psu does not have the requisite aux pcie power lead, then it likely does not have sufficient power available at 12v where the graphics card needs it.
Do not believe the power wattage stamped on a cheap psu.
First of all, they lie. Next, the wattage may not be delivered at 12v where modern processors and graphics cards need it.

The big danger here is that your psu may not have sufficient protective circuitry to protect your other parts if the unit should fail under load.
 

Krotow

Notable
Oct 2, 2019
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Straight and short - get 550W+ PSU with proper PCIe 6-pin connector cables.

Don't bother about things which will not work anyway and can free you from your hardware easy peasy. Those Molex crutches for GPU will not work because:
  • PCIe on motherboard have not enough power to power GPUs like GTX 960 (that is why they have separate 6-pin 12V connectors);
  • and your current PSU is not powerful enough to power these GPUs - and is not intended for that too because it lack proper cables.
 

Karadjgne

Titan
Ambassador
Max current for a 4pin molex 18ga is 11A. At 12v that's 132w.

Max current for a 6pin pcie is 5A per pin, 10A used, 120w.

You can use a single molex to power a 6pin gpu. That's not the issue. The issue is in the adapter, which very rarely use 18ga wire, more common is the use of 20/22ga wires and non-standard pins, which lower current ability seriously.

The smaller the wire/cheaper the connection, the larger the resistance to current. Current through a wire causes heat from resistance. As heat rises, so does resistance. Which raises current, which raises heat, which raises resistance,........ And the next thing you have is a burning chunk of plastic inside your pc.

It's not that adapters don't work, they do, they are used quite frequently for many things. It's that the likelihood of using an improper adapter, from some cheap as possible supplier who cut every corner possible to save a few ¢ per unit, is astronomically greater than using the proper adapter for the needs.

Common sense dictates that if a psu does not have the correct wiring for your intended purpose, the psu itself is not intended to suit your purpose.

You've got 2x strikes against using this combination, a third will likely end up with damages somewhere, not excluding the possibility of a burned up pc.
 
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