video cards and power supplies

[clawhusker]

I see video cards that say 300 watt power supply recommended or required, yet I read of people using lower rated power supplies successfully. Can anyone explain how a video card draws so much power? Isn't it just running a cooling fan, or is the card somehow pulling power through the motherboard?

If anyone can point me to a website that explains this, please do.

 

[Maddscientist]

Welcome to Anandtech Claw....Excellent Question!

Perhaps some of our electric dwelvers can answer that question and be more specific than I can be but I'll give it a shot.

I think that the whole recomended wattage is simply taking into consideration your other components such as 2 CD drives, Processor, Standard Harddrive, Standard Case Fan Load, Mis sound card and input devices, ext ext. Then they add the video card find out the max wattage load and add 50 watts just to be safe. This is simply me talking out loud however so lets let the experts answer

 

[Nohr]

Here's a handy link: Power Supply Wattage Calculator

Video cards need power to run like any other electrical component. The majority of cards get power through the AGP or PCI slot. However, many high end cards require more power than an AGP slot can provide. These have a molex connector on the card which lets it get power directly from the PSU using the same 4-pin power cables that you'd normally plug in to drives. In general, the faster the video card, the more power it consumes.

 

[modedepe]

When they say a 300watt psu is required, they're taking into account an average system. Probably 1 hd, 1 cdrw, 1 dvd, mobo, cpu, 2 case fans, etc. So the 300w is being divided among these components; it's not all going to the video card. And then on the video card it needs more power than just that for the fan. You have many components built into the circuit on the card that are all using electricity, the main user being the gpu, but you also have the ram, caps, etc. Now many people can run with far less than the recommeneded psu. This is primarily because the recommened 300w is just an estimate. The psu you have could be of much better quality than the one they are taking into account. Or, you could have components that use less power than they're assuming.

 

[LaughnCynic]

Originally posted by: Nohr
Here's a handy link: Power Supply Wattage Calculator

Now that's a handy little page... Thanks.

 

[QAGuy]

Thanks for the link, Nohr!