Only using a 4-pin power supply plug on an 8-pin motherboard

[mazeroth]

I built a 3570k HTPC almost 6 years ago using an MSI Z77A-G41 motherboard. I took the PC out to clean out the dust and noticed that the power supply I used (Antec Earthwatts 430) only had a single 4-pin motherboard plug and that's all I used, even though the motherboard has an 8-pin (4+4). It fit on the right side of the plug so apparently when I built it I plugged it in, said a prayer, and have never had a problem.

I am able to overclock the chip to 4.3 ghz, which isn't the best for a 3570k, and knowing I'm using a budget Z77 board. Do you think only using the 4-pin connector is causing me problems? Does the motherboard account for this? This power supply is about 10 years old and I can pick up a brand new EVGA BR 450 for $20, shipped.

Thanks.

 

[SamirD]

I'm curious about this too as I ran into the opposite problem with a power supply that had an 8-pin and I had to get a splitter to get just the 4-pins I needed.

 

[Brian_B]

It's 2x 4-pin connectors providing additional 12V sources - they have the same pinout - just redundant cables so that it can provide more amperage to the CPU/motherboard. They ~probably~ come together through the same 12V header to the VRMs on your phased power circuitry for the CPU, but that particular design would depend on your motherboard.

If you haven't had a problem, yay. It ~could~ be limited your overclock -- as you would see additional voltage droop compared to having the proper power connection, but I doubt it is having a significant impact. Your bigger risk is in melting a plastic connector somewhere in trying to overclock - the CPU is going to pull what it's going to pull, and if your trying to suck a watermelon through a garden hose, something's gonna give somewhere.

 

[SamirD]

Thank you for the insight and photo showing the potential issue.

 

[bigdogchris]

Are you speaking about EPS power connector for CPU current?

If you are not OCing or using a CPU with TDP anywhere near the maximum the board allows, 4 pin should be fine. I have a build right now only using 4 of 8 pins (it's AMD though). If you are going to do any tweaking at all you should fully populate the power connector with an appropriate PSU connection (not just split 4 to 8).

 

[defaultluser]

Yeah, they added the 4-pin 12v CPU connection when Pentium IV CPUs were exceeding 100w stock. It was expanded to 8-pin for more power-hungry workstation CPUs.

As long as you're not overclocking excessively, you should be fine with 4 pins.

The 4 pin supplies 155 watts, and the 8 pin supplies 235 continuous watts.