Power Supply length?

[SpringerSpaniel]

According to the Seasonic site you’re only getting one molex power cable with a GX-1200 and it only has three outputs but the HL15 PCB wants four.

https://www.msi.com/Power-Supply/MEG-Ai1300P-PCIE5

Looks like this is also 160mm and comes with a molex power cable with four outputs.

@Joe

If you are sourcing your own power supply, you can use this as a minimum guideline. It is especially important to ensure you have at least 20A of 5v power.

Edit: Both options seem to support 25A on the 5V rail.