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Question

What has power supply to do with PCI cards?

Jul 5, 2015 7:04PM PDT

I searched a PCI video card for my old computer without PCI-E slot from the net recently and found 2 different cards with different power requirements that made me surprised.

One of them needed a 400 Watt power supply and other 300 Watt.

I just didn't understand why one needed 100 watts more than the other since a PCI slot can only provide 25 watts at maximum. That means both cards cannot draw more than 25 watts from the power supply, then what is the meaning of the 100 watts difference?

Discussion is locked

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Clarification Request
what cards?
Jul 5, 2015 7:26PM PDT

PCI cards I don't see with extra power plugs on them. If that is recommended PSU power and no extra power plugs on the cards, then I'd not worry about it much between them. Probably just an out to blame a PSU if the card isn't working.

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Answer
It means they have an auxiliary power plug
Jul 5, 2015 7:13PM PDT

which must be provided by the PSU. Check to see if you have it first on your PSU.

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Answer
Or one maker has a decent engineer.
Jul 5, 2015 8:38PM PDT

Let's say your car can go 100 MPH. A decent engineer will tell you to not try to run it at 100 too long. Another will reduce the top speed to 80 to keep you from pushing the limits.

Same with power supplies. For long life I run a PSU at 50% or less. For economy I fit one up to 75% of capacity. Beyond that I void the warranty and tell them they are asking for trouble.

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Answer
Mybe they are trying to...
Jul 10, 2015 6:04PM PDT

"modernize" an old card. I am curious, how much?