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Basic question about PSUs and the video cards they power

Last response: in Components
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January 13, 2008 5:42:31 AM

So. I'm planning on upgrading my current AGP card to a Sapphire x1950 PRO for the AGP slot. (overview of the card here) http://www.sapphiretech.com/us/products/products_overview.php?gpid=168

I currently have this PSU http://www.newegg.com/Product/Product.aspx?Item=N82E16817702003

Now. Here's my question. The x1950 says the recommended power requirements is 30a on a 12v rail. And looking at the pictures of the video card itself, I see two connectors for power. My power supply has 2 12v rails, each with 20a. Do they expect me to plug up both 12v rails to the card or what?

I'm confuzzled on this, I've built my own computer, but I've dealt with video cards that had only one power supply connecter and never a video card with that high an amp recommendation.

Anyone help me with this newbie question? I'd appreciate it!
January 13, 2008 7:10:10 AM

To reach maximum efficiency both 12v rails need a load on them, for best results the more balanced the load the better.
I buy single rail PSU's so as not to have this problem.
Strike a good balance with your rails and you should not have problems.
What the 30amp guide is there for is to let you know that your system amperage usage should be under 30Amps with the video card installed.
As long as you have balance in the system, plugging in both rails into the video card will not hurt anything. And your system just might be more stable.
a b ) Power supply
a c 358 U Graphics card
January 13, 2008 7:20:49 AM

First, the recommended power requirement for the X1950 is for the entire system not just the video card. The X1950 itself only uses about 66w at stock speed; thats 5.5 amps.

Second, since PCs varies from to person to person video card companies generally recommend more power than necessary (unless you really have a power hungry system).

Third, you cannot simply add the amps listed on the back of power supplies. The BFG power supply probably has 32 - 36 amps max, but there not enough information on the sticker.
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