Insignificant 1 Amp!?

[Volter]

Can be 1 Amp significant when on the box(video card) says 18A on +12V (350W) rad while on the power supply says 17A on +12V max (500W) !?
Thanks.

[MrAl]

Hi,

Not sure what you mean or how you got your power numbers...
Perhaps you can restate your problem and ask again?

[Volter]

My power supply is 500W and on the +12V rail it delivers 17A. On the video card it says I need on the +12V rail to deliver 18A!?
I do have installed the video card and it is working now. I guess, I would need the full 18A if I would be putting lots of demand on the video card like playing some heavy duty games.
Thanks.

[Volter]

OK, I found out as long there is another +12V rail with some Amps available then it will support the 18Amps needed.
Thanks.

[haklesup]

It depends on what you are doing with the card. In general CMOS IC chips consume power proportional to the clock rate and functions being performed within them, graphics chips and processors operate over a wide spectrum or power requirements. Its likely that the dynamic IDD (supply current when its doing something) is somewhat less than the max for most instances. There may be times like when playing full action video games with high resolution and 3D rendering that the card will be used to its maximum capability and thus max IDD. You'll probably be safe but if your PC crashes or locks up during intensive video applications, you may want to take a look at this again.

I'm kind of surprised it needs so much power on the 12V side. I would have expected the 5V or 3.3V supplies to bear much of this requirement. 12V is usually only used in analog op amp derived circuits but may be used in the VGA driver output section. Please post a link to your card's user manual or technical specifications and I may have more to comment. It may be that you need to run dual monitors to hit this mark.

[reloadron]

haklesup wrote in part:

I'm kind of surprised it needs so much power on the 12V side. I would have expected the 5V or 3.3V supplies to bear much of this requirement. 12V is usually only used in analog op amp derived circuits but may be used in the VGA driver output section. Please post a link to your card's user manual or technical specifications and I may have more to comment. It may be that you need to run dual monitors to hit this mark.

Yes, it is surprising but pretty much how things are with today's graphics cards. The big power demand is on the 12 Volt bus.

Example of ATI card power requirments.

The suggest power supplies in the above link take into consideration the other system requirments but as can be seen these cards (the higher end ones) draw considerable 12 Volt power. Very high end game systems will sometimes run a pair of cards and up to 4 cards. Cards that need more power use additional PCI Express connectors for additional 12 Volt power.

Ron