Using a 20+4 pin connector with a 24 Pin Motherboard

[gychang]

My new gigabite MB has 24 pin connector slot, my older powersupply has only 20 pin power connector, and a separate 4 pin connector (ATX 12v).

My MB specifies this 4 pin connector be connected into a completely separate slot rather than the available slot in the main 24 pin slot. In my case does the 24 pin connector be left with only 20 pin connected?

gychang

 

[SinxarKnights]

right, but that can cause some issues. Such as blue screens, random shutoff, low performance and just plain failure to boot.

the 20+4 is like a 24pin except the +4 is detachable for older motherboards with only a 20pin power socket.

the 4 pin connector you have does NOT plug into the main power socket.

 

[VirtualLarry]

It will work, like plugging in a 4-pin ATX12V connector into half of an EPS12V (8-pin) mobo socket, but it supplies less power to the motherboard. So if the motherboard requires extra power to operate, then it won't work properly. You would have to try it and see if it works.

 

[vailr]

Check eBay for a 20 pin to 24 pin PSU socket adapter.
Can be under $3 shipped, from Hong Kong.

 

[Blastman]

The ATX +12v 4-pin connector does not plug into the 24 pin connector on your MB … (it wouldn't fit anyway as the pin configuration is different). There is a separate 4-pin connector on the MB where the ATX +12v 4-pin connector goes to provide extra power for the CPU. On newer MB's it's an 8-pin EPS connector.

See … all about PSU connectors

You can plug a 20-pin ATX into a ATX 24-pin on your MB, it's pin compatible, and it will work without the extra 4 pins. The extra 4pins added to the ATX 20-pin connector to make the 24 ATX includes an additional +12v pin (and a 3/5v pin) because the original 20-pin ATX only has one +12v pin on it. As newer CPU's came out in the early 2000's they moved towards using more 12v power and less (3/5v), and more power was needed on the +12v connection. Both +12v pins feed the same power rail on the MB, which is why it works.

One caution though. A single molex connector pin is rated for 6A (amps) x 12V = 72W (watts). With the new high powered CPU's, this may not be enough in some cases, and one would be pushing more than what the single 12v molex pin is rated for. ( the two +12v pins of the ATX 24-pin can provide double -- 144 watts total).

In this xbit test, a dual core E8600, 3.3Ghz, + RD 4850 graphics card managed to pull just under 4A peak (about 45 watts) from the 24-pin ATX 12v connection. So in this case a PSU with just a ATX 20-pin connector would suffice with room to spare. But if one did some extreme overclocking and overvolted the stock CPU, one could probably get close to the 6A (72 watt) limit for just one molex 12v pin on the 20 pin ATX connector for this system.

On the quad core system, i7-920, the maximum draw from the ATX 24-pin connector on the 12v lines was over 72 watts, which means a 20-pin ATX connector with only one 12v pin would not be sufficient.

As mentioned, you can get a 24-pin adapter, but it still means that only 1 +12v pin (split into 2 feeds) is powering the MB. So you still have the 72 watt limit and probably wouldn't want to power a quad core system with an 20 - 24 pin ATX adapter.

 

[gychang]

thanks Blastman, now I understand.

gychang

 

[Aluvus]

Check eBay for a 20 pin to 24 pin PSU socket adapter.
Can be under $3 shipped, from Hong Kong.

And what will that accomplish?

 

[VirtualLarry]

One caution though. A single molex connector pin is rated for 6A (amps) x 12V = 72W (watts). With the new high powered CPU's, this may not be enough in some cases, and one would be pushing more than what the single 12v molex pin is rated for. ( the two +12v pins of the ATX 24-pin can provide double -- 144 watts total).

Interesting. For my WHS server (not built up yet), I am using a EP35C-DS3R board, which came with a Q6600 in it when I bought it from someone. I decided to use an Enhance ENP-5150 PSU 500W that I had too. It has six SATA, and plenty of molex connectors. Unfortunately, it only has 8-pin EPS12V connector, and 24-pin ATX connector. The motherboard has a 24-pin ATX connector, but only a 4-pin ATX12V connector.

So I'm using a molex-to-ATX12V adaptor. For powering a (non-OCed) Q6600. If that's only rated for 72W, and I'm sharing the wire to that molex with some HDs too, then that may be a bit out of spec. I think that the Q6600 is a 125W TDP CPU.

Maybe I should take the Q6600 out, and put in an E5200? Or maybe I should buy the proper adaptor, to go from EPS12V to ATX12V.

Edit: That's what I did. Ordered some of these: http://www.newegg.com/Product/Product.aspx?Item=N82E16812198024

 

[Gillbot]

Check eBay for a 20 pin to 24 pin PSU socket adapter.
Can be under $3 shipped, from Hong Kong.

And what will that accomplish?

I was wondering the same thing. The adapter will only add resistance and isn't needed IMHO. If it wont run without the adapter, odds are the PSU isn't gonna be up to task even with it.

 

[dbcooper1]

I was wondering the same thing. The adapter will only add resistance and isn't needed IMHO. If it wont run without the adapter, odds are the PSU isn't gonna be up to task even with it.

You're moving the weak link in the +12V power distribution off the motherboard and into the power supply.

 

[Aluvus]

I was wondering the same thing. The adapter will only add resistance and isn't needed IMHO. If it wont run without the adapter, odds are the PSU isn't gonna be up to task even with it.

We have a winner. The only useful thing that this type of adapter can accomplish is that if the motherboard is looking for voltages on the extra 4 pins, it will see them. The adapter will otherwise just add a little extra resistance and some new points of failure, and make any power problems worse rather than better.

You're moving the weak link in the +12V power distribution off the motherboard and into the power supply.

And how are you doing that, exactly?