Question Powering new GPU with a PSU that only has two remaining PCIe ports ?

[HeyOldMan]

Hello everyone,

I hope you’re all doing well. I have a question and would really appreciate any advice, as I urgently need some help before installing my new GPU.

My system specifications:
PC Case: NZXT H6 Flow RGB
CPU: Ryzen 7800X3D
CPU Cooler: Be Quiet! Dark Rock Pro 5
Motherboard: ASUS ROG STRIX X870E-E GAMING WIFI AMD AM5 ATX
PSU: Corsair RMe Series RM850e 2023 model
Current GPU: RX580 (in use now)

I recently purchased a new GPU:
ASUS TUF Gaming Radeon RX 7900 XT OC Edition 16GB GDDR6

My concern:
This new GPU requires 3× 8-pin PCIe power connectors.

However, my PSU has only 2 remaining PCIe output ports available for the GPU cables.

My question is:

If I connect:
One cable to the first PSU PCIe port, and split it using a pigtail (dual 8-pin) to power two of the GPU’s 8-pin connectors, and then connect a second cable to the second PSU PCIe port for the remaining single 8-pin connector, will this setup be safe and sufficient to power the GPU?

I haven’t unboxed the GPU yet because I want to be completely sure this configuration won’t cause any problems such as overheating cables, melting connectors, or damage to the GPU itself.

I’m a bit nervous about this and don’t want to risk harming my components, so I’d be very grateful if someone with experience could advise me whether this method is acceptable or if I absolutely need three separate PCIe cables plugged into the PSU.

Additionally, the top two PCIe ports on my PSU are already occupied by cables powering the
Asus ROG Strix X870E-E Gaming WiFi motherboard.

Any guidance or suggestions would mean a lot to me. Thank you very much for taking the time to read this, and I look forward to your replies.

 

[Lutfij]

Welcome to the forums, newcomer!

Thumb rule with PC building, if your PSU lacks the necessary connectors for your build, you either have;
a| the wrong PSU for the job
or
b| the wrong components for your build.

PSU: Corsair RMe Series RM850e 2023 model
https://www.corsair.com/us/en/p/psu...wQShW-35k5FJz3sx7pN7c2gJg2e45NaYasWqo_IRCA7Y4
So you get;

1 of these(8pin PCIe harness) and

1 of these(2x 6+2pin PCIE harness).

Or you could pick up 3 of these;
https://www.corsair.com/us/en/p/pc-...connector-type-4-gen-4-aca-a-black-cp-8920243
for the sake of uniformity or maybe just 2, as your PSU has 4 outputs for PCIe harnesses.

 

[HeyOldMan]

thanks for sharing the pictures. Just to confirm, is it safe to use the dual 8-pin pigtail cable (the 2nd picture) for 2 of the GPU connectors, along with one separate 8-pin cable for the third connector? Or would you recommend using 3 separate cables instead? If I go with 3 separate cables, that would mean I need to remove the second CPU power cable from the motherboard to free up a PSU slot—is that okay to do?

 

[ilukey77]

Its not recommended to daisy chain GPU cables from PSU ..

In other words, 3 connectors on GPU, 3 separate cables from PSU

 

[beyondlogic]

thanks for sharing the pictures. Just to confirm, is it safe to use the dual 8-pin pigtail cable (the 2nd picture) for 2 of the GPU connectors, along with one separate 8-pin cable for the third connector? Or would you recommend using 3 separate cables instead? If I go with 3 separate cables, that would mean I need to remove the second CPU power cable from the motherboard to free up a PSU slot—is that okay to do?

You need a psu with 3 separate cables 8 pins each

1 cable provides 150w of power

 

[--SID--]

Daisy chained cable is totally fine. Corsair cables are decent with 16AWG to the first connector and HCS terminals. One daisy chained cable can provide 300w, 150w on each connector.

 

[geofelt]

In theory, a cable with two 8 pin(or 6+2) connectors can be used.
They are intended to allow a 8 + 6 pin connection.
But, if the power draw is sufficient, with two 8 pin connections, the capacity of the cable may be overwhelmed.
I suggest you contact Corsair with your issue. They are the experts on their products.

I suspect that you may want to use a stronger PSU . 850w may not be sufficient to handle peak power spikes from a strong gpu.