I recently bought an ASRock PRO 650B 650W ATX 3.1 power supply. It includes a single PCIe cable with two 6+2-pin connectors, often called a daisy-chain cable. I'm choosing between a used or new Radeon RX 6700 XT 12GB and an Intel Arc B580 12GB, with a budget of about $300 USD or ₱20,000. The RX 6700 XT typically uses two 8-pin connectors, while many B580 models also use two even though some need only one. Is it safe to power either card using the two 6+2-pin connectors on this power supply? I'd also appreciate any relevant advice about compatibility or setup.
3 Answers
Yes, a daisy-chained PCIe cable should be fine for these cards. The RX 6700 XT and Arc B580 are well within the practical power range of a good 650W supply. Just make sure both 6+2 connectors are fully seated, and don’t use adapters or mix modular cables from another power supply.
An Arc B580 can work, but Intel cards benefit significantly from Resizable BAR being enabled. Check that your motherboard firmware and CPU support it, then enable Resizable BAR and Above 4G Decoding in the BIOS if available. Without it, performance can be noticeably worse.
My motherboard is a Biostar B550MHP. I’ll check its BIOS options and confirm that my CPU also supports Resizable BAR before choosing the B580.
The RX 6700 XT normally uses two 8-pin PCIe plugs, so the two 6+2 connectors on your cable match it. For the B580, follow the exact connector requirement of the specific model, since some versions use one 8-pin and others use two. Your 650W unit should be adequate as long as it’s functioning properly and the rest of the system isn’t unusually power hungry.
That’s reassuring. I was mainly worried because I’ve seen warnings about daisy chains, but I’m avoiding much more power-hungry cards such as the RTX 3080.