[SOLVED] PC won’t power up with GPU plugged in ?

[Eyoung74]

Please help! My son and I just completed or first new build. The PC won’t power up when I plug the GPU in. If I unplug the GPU the pc will power up. I can see the GPU light up when it’s not plugged in. As soon as I plug it in I get nothing when I press the power button. Any help would be greatly appreciated

Asus Rog Crosshair VIII Dark Hero​

AMD Ryzen 7 5800X3D
Corsair RM 850 PSU
Gigabyte RTX 4070

 

[Deleted member 2731765]

Did you properly connect all the PCI-E cable connectors into the GPU's slot ? Does your GPU require a SINGLE 16-pin 12VHPWR connector ? If yes, then you might need an adapter if your PSU lacks it.

 

[Eyoung74]

Did you properly connect all the PCI-E cable connectors into the GPU's slot ? Does your GPU require a SINGLE 16-pin 12VHPWR connector ? If yes, then you might need an adapter if your PSU lacks it.

I thought I plugged all the PCI-E cables in correctly. The Pc is getting power just not when GPU is plugged in. The GPU came with the single 16 pin adapter that split into two. I plugged the pci-e cables to the adapter and then to the PSU.

 

[geofelt]

Your motherboard has two cpu eps connectors. One 8 pin and the other 4 pin.
Both are likely required.
Your symptoms are that of not having both connected properly.
Are they fully in and latched? At both ends?
The 4 pin will have the extra 4 pin dangling.

When you say the GPU is not plugged in, what do you mean?
Not in the x16 slot, no aux power to the card, or no monitor plugged in to the card?

 

[Eyoung74]

Your motherboard has two cpu eps connectors. One 8 pin and the other 4 pin.
Your symptoms are that of not having both connected .

When you say the GPU is not plugged in, what do you mean?
Not in the x16 slot, no aux power to the card, or no monitor plugged in to the card?

Not plugged in meaning the 16x unplugged from the GPU.

 

[Eyoung74]

Not plugged in meaning the 16x unplugged from the GPU.

And you’re correct, I don’t have the 4pin connected. I didn’t know that one needed to be connected. I’ll plug the 4pin in when I get home. Thank you

 

[Misgar]

I was under the impression the second EPS connector was only required if you intended to apply a moderate to heavy overclock on the CPU. The PC should start up with only one 8-way cable, especially if no overclock has been configured.

Of course the BIOS might monitor both EPS connectors and prevent booting with only one cable, in the same way most GPU cards won't start if you fail to connect all the power cables.

The OP states "If I unplug the GPU the pc will power up" but we don't know if he had a monitor connected to another graphics port and the BIOS screen appeared, or if the mobo was running without a GPU of any kind.

Could I ask if the 4070 is plugged into the first PCIe x16 slot (closest to the CPU) or into the second or third slot which might only have 4-lanes of PCIe connectivity.

It might be worth trying any PCIe graphics card to hand, even if it's a GT710.

 

[Eyoung74]

I was under the impression the second EPS connector was only required if you intended to apply a moderate to heavy overclock on the CPU. The PC should start up with only one 8-way cable, especially if no overclock has been configured.

Of course the BIOS might monitor both EPS connectors and prevent booting with only one cable, in the same way most GPU cards won't start if you fail to connect all the power cables.

The OP states "If I unplug the GPU the pc will power up" but we don't know if he had a monitor connected to another graphics port and the BIOS screen appeared, or if the mobo was running without a GPU of any kind.

Could I ask if the 4070 is plugged into the first PCIe x16 slot (closest to the CPU) or into the second or third slot which might only have 4-lanes of PCIe connectivity.

It might be worth trying any PCIe graphics card to hand, even if it's a GT710.

Ok so I plugged in the 4 pin connector on the Mobo and the system powered up. All is good now. Thanks for the help

 

[geofelt]

Ok so I plugged in the 4 pin connector on the Mobo and the system powered up. All is good now. Thanks for the help

 

[Misgar]

That's useful to know. Thanks for the update. I'll be more careful with my choice of PSU on my next build, if it might need both EPS sockets to be populated.