Adding D5005 PAC to Server Causes Boot Error

We have a new D5005 PAC that we want to add to an existing server (S2600WF). The server had a PAC with Arria 10 GX and it booted and worked fine. But when we add the D5005 card, it doesn't even boot and the beeps indicate a power fault based on this link. The power supply is 1300W, so I doubt that that's the issue. I followed the instructions in the quick start guide page, i.e., enabling SR-IOV and Virtualization Technology in BIOS, and using a 12 V auxiliary power cable to power the card. I tried various PCIe slots on the motherboard, and removed the PAC with Arria 10 GX, but in all cases got the same beeps (1-5-4-2). What am I missing here?

Any help would be appreciated.