Dell power supply question.

[ComGaunt]

I ran a Nvidia 660GTX graphics card on my Dell XPS 420 with a 375 watt power supply for a couple of years. Nvidia listed 450 watt power supply as a requirement but I did not have any problem at all.

Now I have a XPS 8700 with a 475 watt power supply and I am looking at buying a Nvidia GTX 970 graphics card.

The GTX 970 requirements are set at 500 watts. I looked at some of the reviews of both the GTX 660 and the GTX 970 and the total load power use of a system using the Nvidia GTX 970 is 50 watts higher than that of the GTX 660 at around 300 watts total.

Since I was able to run the GTX 660 with a 375 watt dell power supply, I don't see any issue running the GTX 970 with the 475 watt dell power supply. Am I missing something with people buying 750/1000 watt power supplies?

 

[phasseshifter]

it should run the card ok but you may be pushing the supply to it`s limits specially running games a 750 watt supply would be better..and not being pushed to it`s limit`s

 

[dave_the_nerd]

1) Dell doesn't make the power supplies, they just buy them from somebody else.

2) 970 max TDP is only 5w higher than the 660.

3) Companies selling graphics cards pad their requirements A LOT to play it safe. While a typical system with a 970 might only consume 300-350w, not all 400w PSUs are created equal. In fact, a lot of them probably can't provide anywhere close to 400w. Meanwhile, you don't know if some jerkoff with a 400w PSU does or doesn't have 200w worth of hard drives and mood lighting or an overclocked CPU pulling 50w more than it should be. So they basically figure how much power the average person would need, and double it, and THAT's the PSU "minimum" requirement.

People buying 750-1000w PSUs are probably overbuying, but if you crammed enough graphics cards into a case, you could certainly burn that.

 

[dave_the_nerd]

it should run the card ok but you may be pushing the supply to it`s limits specially running games a 750 watt supply would be better..and not being pushed to it`s limit`s

A power supply is most efficient at around 80% load, so if you're "right-sizing" your PSU for the best power efficiency, you actually do want to come pretty close to the limits.

 

[ComGaunt]

Thank you Dave the Nerd for your awesome answer