Any power supply experts here?

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Billiam29 Senior Member • Posts: 2,450
Any power supply experts here?

Anyone here specifically knowledgable on split rail power supply designs?

The Be Quiet! Dark Power 12 PSU I purchased for my new build is a split rail design with four different 12v rails. Image below.

If your motherboard has a single 4 pin connector for CPU power, then the connections on the PSU look like this:
- motherboard 24 pin and CPU 4 pin on rail 12v1

If your motherboard has a single 4 pin connector and an additional connector for CPU power (4 or 8 pin), then the connections on the PSU would look like this:
- motherboard 24 pin and CPU 4 pin on rail 12v1
- second CPU power (4 pin or 8 pin) on rail 12v2

If your motherboard has two 8 pin connectors for CPU power, then the connections on the PSU look like this:
- motherboard 24 pin on rail 12v1
- *both* of the 8 pin CPU power connections on rail 12v2

The MSI Pro Z690-A DDR4 motherboard I chose requires this final arrangement. It has two 8 pin connectors for CPU power. So is this a problem or risk having both CPU power connectors on the same rail?

My rational mind is telling me...
"Don't worry about it. With two CPU power connections in a non-overclocked system, I'm not even remotely close to the 384 watt limit on the rail. Additionally, neither of the rails involved are the same as the PCIe GPU connections."

Having said that, I can't help but wonder if there is some aspect of a split rail PSU design I'm ignorant of which really does benefit...or outright require...having two CPU power connections split acorss different rails.

Dark Power 12 Connections with 12 volt rails labeled:

The CPU power cables supplied with the power supply are:
- PSU "MB" 8 pin to motherboard 4 pin
- PSU "P8" to a motherboard EPS 8 pin
- PSU "P8" to a motherboard EPS 4+4 pin (compatible with 8 pin)

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