FAQ
TL;DR: Molex 12 V lines are rated ~11 A (~130 W); “an additional cable from a single molex can also handle it.” Use the PSU’s native 6‑pin plus one Molex‑to‑6‑pin for the Sapphire HD 7870 XT. [Elektroda, dt1, post #17158006]
Why it matters: This helps builders safely power a 2×6‑pin GPU on a PSU with only one PCIe connector.
Quick Facts
- PCIe power spec: 6‑pin = 75 W, 8‑pin = 150 W; design cabling to these limits. [Elektroda, dt1, post #17158031]
- Typical Molex plug capacity: ~11 A per 12 V line (~130 W) in this context. [Elektroda, dt1, post #17158006]
- XFX Core PRO 450W uses a single +12 V rail; pick Molex from separate harness “beams.” [Elektroda, dt1, post #17157283]
- Sapphire Radeon HD 7870 XT draw: approx. 185 W; account for both GPU 6‑pins. [Elektroda, bogdanzieba, post #17158053]
- 2×Molex→PCIe adapters are inexpensive (“for pennies”) or sometimes included. [Elektroda, dt1, post #17158056]
Whats the best way to power a Sapphire HD 7870 XT with an XFX Core PRO 450W?
Use the PSUs native 6‑pin for one GPU socket. Create the second with a Molex‑to‑6‑pin adapter. Pick Molex plugs from two separate harnesses to spread load. “Select molex plugs on two separate beams.” This balances current on the single +12 V rail. [Elektroda, dt1, post #17157283]
Is a 1 76 pin to 2 76 pin splitter okay for this card?
It can work, but prefer the native 6‑pin plus a Molex‑to‑6‑pin. The PSU has many Molex outputs, and dual‑Molex adapters are cheap. “For me it will do,” yet using Molex harnesses avoids stressing one PCIe lead. Thats the practical recommendation here. [Elektroda, dt1, post #17158056]
How much power can a single Molex plug deliver?
Approx. 11 A per 12 V line, which is about 130 W. With one Molex adapter plus a direct PSU cable, the GPU power path is sufficient. “The theoretical load capacity of the molex plug is 11A per line.” [Elektroda, dt1, post #17158006]
What are the PCIe PEG connector limits I should design to?
PCIe 6‑pin is 75 W. PCIe 8‑pin is 150 W. “In practice certainly much more,” but follow spec when planning wiring. On a decent PSU, “there should be no problems” when you route cables sensibly. [Elektroda, dt1, post #17158031]
Will a 450 W XFX Core PRO handle Pentium G4560 + HD 7870 XT?
Yes. With a decent unit and thick cables, there should be no issues powering this setup. Keep one native PCIe 6‑pin and use one Molex‑to‑6‑pin as advised. “There should be no problems” with proper cabling. [Elektroda, dt1, post #17158031]
Do I need to use both included Molex to 6 pin adapters?
No, not with this PSU. Theyre provided so each GPU plug can be fed from separate lines when a PSU lacks PCIe leads. “Best to connect each on a separate ‘line’,” which explains why two adapters are included. [Elektroda, KSRhaziel, post #17156944]
How should I choose which Molex connectors to use?
Use Molex plugs from two different harnesses (“beams”). This distributes current and avoids stacking load on a single peripheral chain. Quote: “Selecting molex plugs on two separate beams.” This matches the PSU’s single‑rail design and thick cabling. [Elektroda, dt1, post #17157283]
Can I run both GPU 6 76 pins from one peripheral chain?
Avoid that. The guidance is to feed each required plug from a separate line to distribute current. The manufacturer packs two adapters anticipating this need when PCIe leads are missing. “Connect each… on a separate ‘line’.” [Elektroda, KSRhaziel, post #17156944]
If I only have one free Molex, is that still okay?
Yes. One Molex‑to‑6‑pin can handle the extra feed because the other GPU plug is powered directly from the PSU. “An additional cable from a single molex can also handle it.” Keep wiring tidy and secure. [Elektroda, dt1, post #17158006]
Is a dual Molex to 6 pin adapter better than a single Molex one?
Yes, if your PSU has enough Molex plugs. “Yes, I would use it with a power supply with enough molexes.” It shares current across two connectors on the peripheral side. That adds margin under load. [Elektroda, dt1, post #17157826]
How do I wire this safely? (3 steps)
- Plug the PSU’s native 6‑pin into one GPU socket.
- Use a Molex‑to‑6‑pin for the second socket.
- Select Molex plugs from two separate harnesses (“beams”) to spread load on the single +12 V rail. [Elektroda, dt1, post #17157283]
Does splitting one 6 76 pin into two increase available power?
No. One 6‑pin is still a 75 W spec feed. A 1×6‑pin→2×6‑pin splitter does not raise that capacity. For a 185 W class card, prefer the native 6‑pin plus a Molex‑to‑6‑pin. [Elektroda, dt1, post #17158031]
What is the HD 7870 XTs approximate power draw?
Approx. 185 W for the Sapphire Radeon HD 7870 XT With Boost. Size your cabling and connector plan around that draw. Use one PCIe 6‑pin plus one Molex‑to‑6‑pin as discussed. [Elektroda, bogdanzieba, post #17158053]
Are the XFX Core PRO 450W cables robust enough for this setup?
Yes. The unit has a single 12 V line and thick cables noted by contributors. That supports the recommended Molex‑plus‑PCIe cabling approach. Follow the separate harness guidance for best results. [Elektroda, dt1, post #17157283]
