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Power connections to the motherboard, why so many?

Stageman

Junior Member
So I have a new AMD single slot CPU mobo with one PCI-E slot for a video card. The video card is a single GPU core.

The mobo has a 24 pin power connector, a four pin connector next to the CPU and also a auxiliary video power connector* just above PCI-E video slot. The video card itself has a six pin power connector.

So if I plug all power connections in, that is a total of four. It seems a bit odd to me.

The 24 pin main power (already a step up from the last generation 20 pin connectors) and the 6 pin power connecting to the video card seem alright but then there is the extra 4 pin power for the CPU. OK, the 4 pin power connection for the CPU I can understand even though it is a single CPU board, but the last connection of the auxiliary video power connector started to make me question this whole thing.

If I got a 6 pin power already plugged into the video card and there isn't another slot even for a second video card, why is that aux slot on the mobo? I suppose it could be for dual core GPU's but I thought those cards already came with two 6 pin power inputs. If it was a SLI or Crossfire motherboard it still is a bit confusing since each video card has a power input.

Rather perplexing if you ask me. Also the way the motherboard manufacture referenced the auxiliary video power connector was to say that I might experience less than ideal performance if it was not plugged in. Gee, that is like kinda pregnant 😛.

So whats the deal with that last aux power input, just plug into it and forget it or is it superfluous as it seems to be given my description? I didn't find any cautions in the motherboard or video card manuals but multiple power input paths raised a bit of concern.

* (The sex on the pins is turned around but you get the idea.)
 
The main reason for so many power connections on a motherboard, is circuit board traces can only carry so much amperage, before they become too wide and take up room where other signal traces may go. This even applies to dual and multilayer boards, as it makes it harder
to use through holes between sides. So in a lot of cases, it is easier and more effective to put the power pins near where the high current draw
items are on the circuit board.
 
Originally posted by: TheKub

??? I'm not seeing this Aux power connector your talking about.
Oh, this is very interesting. I didn't fully realize it at first but Newegg sent me a different version than what I ordered. I'm not sure yet but I think I got a better version. I'll have to looking to the southbridge chipset difference.

http://www.biostar.com.tw/app/.../content.php?S_ID=364#

I had noticed somethings different than what I remembered but didn't give it enough thought till your question.
 
I believe that extra AUX is for SLi or CF (I remember seeing it on old Nforce SLi boards)

4 or 8pin EPS12v is for the Cpu to get more 12v power on its own rail
20 or 24pin ATX is for the board to supply power for its own uses

It kinda went

20pin ATX -> 20pin ATX + 4pin EPS12v -> 24pin ATX + 4pin EPS12v -> 24pin ATX + 8pin EPS12v

 
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