Areca 24/4 Internal/External Port Pcie 3.0 12 Gb/s SAS/SATA Raid Controller 2Gb Cache - Manual (Page 28)

HARDWARE INSTALLATION
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Step 7. Connect Power to the Controller (ARC-1883ix only)
There is a 6-pin PCI-E connector on the ARC-1883ix labelled J4.
You must plug in a PSU’s PCI-E cable at all times to supply enough
stable power for the controller.
Figure 2-9, Connect Direct from Power Supply
If your power supply doesn’t have a 6 pin PCI-E power cable then
you can use the adapter to convert two 4 pin peripheral power
cables into a PCI-E power cable. If you use an adapter then be sure
to plug the 4 pin peripheral power connectors into separate power
cables coming from the power supply.