Isn't each 8pin PCIE port can only provide 150w?
In fact, each 8pin PCIE port on a modern PSU can supply over 300W from each port. Thus, 2 x 8pin PCIE ports are more than enough to provide 600W for 12VHPWR.
This is why you see PSU vendors are offering 2 x 8pin to 12VHPWR cables which support 600w.
RTX 4090 is a 450w card. 600w means 133% of 450w.
There is a common misconception that ALL 8-pin connectors are limited to 150W - this is not true. First, we need to differentiate between two connectors:
PSU 8-pin connector - This is the 8-pin connector that you connect to your power supply. This connector can supply over 300W.
PCIe 8-pin (6+2 pin) connector - This is the 8-pin connector you would insert into your graphics card, or the adapter that came with your RTX series cards. The PCI-e specifications have set this connector to being able to handle 150W. In reality it can handle much more, but due to variances in power supply and cable manufacturer’s quality and materials used, the graphics card manufacturers are limited to only drawing 150W per connection.
This is also why you can safely power a GPU that needs two PCI-e 6+2 connectors with a PSU 8-pin connector, since the connector on the PSU end can supply more than 300W, and each of the PCI-e 6+2 connectors only draws up to 150W each.
This is why you see PSU vendors are offering 2 x 8pin to 12VHPWR cables which support 600w.
RTX 4090 is a 450w card. 600w means 133% of 450w.
There is a common misconception that ALL 8-pin connectors are limited to 150W - this is not true. First, we need to differentiate between two connectors:
PSU 8-pin connector - This is the 8-pin connector that you connect to your power supply. This connector can supply over 300W.
PCIe 8-pin (6+2 pin) connector - This is the 8-pin connector you would insert into your graphics card, or the adapter that came with your RTX series cards. The PCI-e specifications have set this connector to being able to handle 150W. In reality it can handle much more, but due to variances in power supply and cable manufacturer’s quality and materials used, the graphics card manufacturers are limited to only drawing 150W per connection.
This is also why you can safely power a GPU that needs two PCI-e 6+2 connectors with a PSU 8-pin connector, since the connector on the PSU end can supply more than 300W, and each of the PCI-e 6+2 connectors only draws up to 150W each.
Updated on: 08/01/2025
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