Multiple 12V Power Rails

[descombobulator]

Just before Xmas I upgraded to a PowerCooler X1950 Pro 512 graphics card; am important factor was that it used less power that competing products. However, I was dismayed to find that the system requirements for this card is for a 450 Watt PSU, with 30A!! on the 12 V rail. I have a Antec 430W model with 20A on 12V.

I have seen in other posts that many people are running their cards with lowed-rated PSUs. However, I'm considering a new PSU so that I can overclock various components and I am puzzled that many of the decent PSUs offer > 30A, but across more than one 12v Rail? So....

1. Is the 6-pin power connector the sole source of 12V for the graphics card?

2. If so, how can it draw power from more than one 12V rail?


Incidently, the 6-pin to 4-pin power convertor that came with the card was an absolute bitch to fit. It took a huge amount of force to get the plug in; I thought I was going to snap the board. How did anyone else get on? Is it a crap plug or crap socket?

 

[ACESHIGH]

My understanding is that it draws some power from the actual PCIE socket & the rest from the 6 pin connector. AFAIK it draws power from only 1 rail. I belive PSU's with one rail the 12v+ has to account for all the pc components whereas with multiple rails its split (say for cpu / gpu) hence each individual rail is lower. Im sure more enlightened people will be along shortly to offer further help & better explanations.

Incidently, the 6-pin to 4-pin power convertor that came with the card was an absolute bitch to fit. It took a huge amount of force to get the plug in; I thought I was going to snap the board. How did anyone else get on? Is it a crap plug or crap socket?

Never had this problem on the couple of cards i have used. They fit snugly, but not too tight.

 

[semi-pro waster]

ACESHIGH is right, it draws power from the motherboards PCI-E slot and because that isn't enough for most cards it also takes power from the 6pin connector.

If your PSU has split rails then you can connect one line to the motherboard and one to the graphics card but if not (like your Antec) then it will all be drawn from the only rail, it makes little difference in this case, your PSU will be fine for that graphics card. Some PSUs also offer the ability to combine the rails manually or more commonly will automatically change to one rail if more power is taken that the split rail can supply.

 

[dmsims]

http://www.playtool.com/pages/psurailhistory/rails.html

HTH

 

[Darkwave]

There is no need to dismay, the requirements on the boxes are wildly exaggerated. I am running an X1900XT on an Akasa 460W, my mate is running his X1900XT on an Antec 380W, so your X1950Pro will use at least 60W less than both of our cards and your PSU will be good enough to run it.

 

[descombobulator]

Thanks very much for the answers, guys. I think I might put off the new PSU for a bit. I need a new hard drive anyway

dmsims: That link makes very interesting reading; a reminder that the manufacturer's spec is often little more than advertising. It pays to dig a little deeper.