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My new computer rig has a power supply with just 1 4-pin connector but the motherboard, a GIGABYTE GA-MA785GM-US2H has an 8-pin ATX 12V power connector.

Is using only the 4-pin connector enough?

Edit:

The motherboard has a 2x12 main power connector and a 2x4 12v power connector for the CPU. According to the manual, its not even supposed to be able to be turned on without the 12V cable.

Edit 2:

  • CPU: AMD Athlon II X3 435 Rana 2.9GHz
  • PSU: 400W OCZ StealthXstream
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Fried Pin Zone. Original 4-pin would occasionally burn the pins. –  Fiasco Labs Aug 30 '13 at 5:55

1 Answer 1

up vote 5 down vote accepted

IT depends on your CPU. The additional 4 pins were added to support the higher power draw of newer (at the time) Core 2 Quads. The 4 pins will happily provide power to most lower end CPUs, but if you have a Quad I would double check the TDP and make sure you can provide enough power with the 75W that the 4-pin can provide and that you don't need the 150W that the 8-pin provides.

Either way, I would upgrade your PSU. You can get a good, brand name, high efficiency PSU with the proper connectors for well under $100 and you will be all set in the event that you upgrade down the road.

Edit: The Rana has a 95W TDP, this means that your CPU will consume 95W on max load. Your 24 pin power connector provides 144W max on the 12V rail. 75 of these Watts are used by PCIe, which leaves ~69W for the CPU (though other components will use some of this so in reality it's probably closer to 60W). This means that with the additional 75W from the 4-pin you can ~135W available to the CPU under max load. This should be plenty assuming you are doing no overclocking and your motherboard and you don't have any other major 12v draws in your system (like an additional video card).

Seriously though, you should still get a new PSU. They can be reused in newer computers if you upgrade and there's no guarantee that you aren't voiding your motherboard warranty even though it should work.

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I have a triple core Athlon II, according to newegg, its rated TDP is 95W, but I believe the OCZ PSUs are reputed to be high efficiency (vs some of those crap PSUs that just claim their peak but are usually overrated by 100W) –  wag2639 May 27 '10 at 15:47
    
@wag2639 - see my edit –  MDMarra May 27 '10 at 15:54
    
thanks. It is a brand new PSU and I have a new 700W PSU lying around also, but it seems overkill for something like this. Its just for my parents to watch SD videos (maybe HD in future). I wasn't even going to add any PCI adapters or additional graphics card. –  wag2639 May 27 '10 at 17:39
    
@wag2639 - Got ya. If that's the case, you should be OK from an available power standpoint. Just keep it in mind if there is ever any flakey behavior. –  MDMarra May 27 '10 at 18:14
3  
I'm curious, if the 75W from the 4-pin wasn't enough, what would happen? Would it damage the motherboard, or just shut off? –  callum Jul 1 '11 at 10:30

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