4-pin ATX plug in 8-pin EPS socket?

[brocks]

Sorry if this is a dumb question, but...

I'm building a new Haswell PC, and I want to use an extra PSU I already have, but the motherboard I'm getting requires an 8-pin EPS socket, and my PSU only has a 4-pin ATX connector (along with the main 24 pin power connector).

So I looked around, and I found several articles and posts that recommended using a 4-pin to 8-pin adapter, like this. Lots of good reviews, people say it works, so I guess I'll get one. Way cheaper than a new PSU.

But then I wondered, if you can do that, why can't you just plug it straight in without the adapter? After all, no matter how many wires the adapter adds, the current is still going to be limited by the original four wires. And the CPU I'm getting has a max power draw of only 54 watts, so it's not like it needs much power anyway.

So, will it work to just plug the four pin plug into either half of the 8-pin socket, or is there something preventing it, like different shaped holes or something. If it will work, does it matter which half of the socket I use?

Thanks for any help.

 

[denis280]

The 4 pin cable only fits at one end of the 8 pin EPS motherboard connector so you can't plug it in improperly. That is, it only fits into one end of the motherboard connector unless you force it. If the cable doesn't go into the socket easily then you're probably trying to plug it into the wrong end. But then again, it's not a good idea to try to run with a 4 pin cable in an 8 pin motherboard anyway.

 

[zir_blazer]

According to this Tom's Hardware article, there DO are Motherboards that are hardwired in such a way that will only work with the full 8 Pin EPS12V or 4+4 ATX12V (Even if you use a 4 to 4+4 adapter):

Some motherboards that utilize an eight-pin +12 V CPU power connector must have signals connected to all eight pins for the voltage regulators to function properly, while most will work properly even if a four-pin PSU connector is attached. In the latter case you will often see that the eight-pin connector has a cap installed over four of the pins, meaning that a four-pin connector can be installed in the exposed portion. Consult the specific motherboard documentation to see if you can attach a single four-pin +12 V power connector (offset to one side or the other) when using lower power processors. If you are using a processor that draws more power than a four-pin connector can supply, then you should ensure you are using a power supply with an eight-pin connector to match the motherboard.

If you're going to use a Processor with low power consumption and the Motherboard is not hardwire like that, you should have no issues.

 

[Seba]

I can not see how would the motherboard detect that you are using a 4 to 8 pin adapter (as long as the adapter has all pins connected and the power supply can deliver the amperage required).

 

[jumpncrash]

It is recoimended for higher load systems, but if you don't use it it's not always going tp cause issues. I knwo with some sytems at work we need to use the 4 top 8 pin adapter. But they have pretty beefy CPUs and 64gigs of ram