Any disadvantages to having a power supply more powerful than the system needs?

[kapalua12]

If a system "needs" say 400 watts and you install a 650 watt gold 80 Plus PS, what's the disadvantage other than wasted money? Will it hurt the system?

 

[(sic)Klown12]

As long as it's a good quality PSU, there shouldn't be any issues.

 

[BoomerD]

If a system "needs" say 400 watts and you install a 650 watt gold 80 Plus PS, what's the disadvantage other than wasted money? Will it hurt the system?

The only disadvantage is the initial price.

The power supply doesn't pull 650 watts from the wall and send it to your components. It only pulls as much as is needed at the time.

If you buy a power supply that is greatly oversized, (say you buy a 1200 watt unit and your system only needs 250-300 watts) then you may run into some inefficiency issues...in that instead of being 80% efficient, it's only 65-70% inefficient...but that's about the worst case scenario.

In your example, your 650 watt power supply will be just fine for a computer that needs 400 watts...and I prefer to have a power supply that's capable of providing at least 20% more power than the system will ever need.

 

[gevorg]

If a system "needs" say 400 watts and you install a 650 watt gold 80 Plus PS, what's the disadvantage other than wasted money? Will it hurt the system?

If system needs 400watts and you instal 650watt gold PSU, thats actually pretty normal, not excessive at all. Installing a 430watt gold PSU would be asking for trouble, lots of trouble.

Give it at least 30% of headroom, 50% is even better if you don't want the PSU fan to be too loud.

 

[Mr. Pedantic]

It depends. As far as I can remember PSUs are more efficient at 50% load, and it's a better usage scenario than being at 90% load in terms of wear as well. So if your PC is going to be constantly at load, then aiming for double your PC's power consumption would be a good idea, I guess. Other than the wasted money from inefficiency and getting a higher-rated PSU than you actually need, there's nothing I can think of.

 

[BoomerD]

Something that I nor anyone else mentioned...be sure to buy a QUALITY power supply from a reputable company using a quality PSU OEM. Do NOT just buy based on total wattage and "Gold 80 Plus."

Power supplies are NOT all created equal...

My recommendations are:

Seasonic
XFX
Corsair (some models, although all are good, some are better)
Antec. (some models)

Most companies use a variety of power supply OEM's to build their units. IMO, Seasonic is the best OEM around for the "smaller" power supplies, (under 1000 watts) so take time to research, ask questions here, and do not buy blindly.

 

[kapalua12]

Thanks guys for the responses!

My system at work is a Dell Optiplex MiniTower 990. It has a 265 Watt Gold OEM 80 plus power supply as it was shipped to me.

I want to add a power hungry video card and have already added 16 GB DDR RAM. I see this thing needing 400 to 500 watts if I go by the GPU manufacturer's recommendation.

Problem is with this Dell, which does state it takes a standard ATX power supply, the dimensions are a few mm off in one dimension that would prohibit me from some supplies since the power supplies are not a standard size exactly and Dell has these aluminum case pieces that might have to be bent out of the way.

Is this normal?

 

[Modelworks]

Problem is with this Dell, which does state it takes a standard ATX power supply, the dimensions are a few mm off in one dimension that would prohibit me from some supplies since the power supplies are not a standard size exactly and Dell has these aluminum case pieces that might have to be bent out of the way.

Is this normal?

That is normal with OEM PC. Sometimes you may have to get something like a dremel tool to cut out parts of the original casing to fit parts bought retail. They use the ATX form factor but that doesn't mean that parts are directly interchangeable . They often had a metal flap, screw hole or something in a different place.

 

[Zap]

Besides the price, if the PSU is not modular the higher capacity the PSU, the more extra cabling you have in your case. If modular, that's just more unused cables that you will lose (and yes I've heard from people losing/misplacing their unused modular cables).

My system at work is a Dell Optiplex MiniTower 990. It has a 265 Watt Gold OEM 80 plus power supply as it was shipped to me.

I want to add a power hungry video card and have already added 16 GB DDR RAM. I see this thing needing 400 to 500 watts if I go by the GPU manufacturer's recommendation.

What is this "power hungry video card" you speak of? What CPU is in it? How many drives?

 

[lehtv]

Efficiency when idling can be a disadvantage. 80Plus specification is done at 20%, 50% and 100% loads; below 20% load efficiency doesn't matter for the efficiency rating. Even Corsair AX750 80+ Gold PSU, which is able to do 89% at 20% load, plummets down to 83% at 10% load. If 750W is overkill for your system, you'd reach better idling efficiency with a lower rated PSU - and thus not only save on the price of the PSU itself, but you'd also save a little on your power bill in the long term.

 

[Fallengod]

Not sure if anyone else mentioned it but, power supplies tend to last longer as well the less stress that was put on them. In terms of longevity, its better to run a system using 200 watts of power 24/7 on a 600 watt power supply vs a 300 watt power supply.

I dont know, I run a corsair TX650 watt psu and my system right now is very budget and has minimal power consumption needs.

 

[Zap]

Not sure if anyone else mentioned it but, power supplies tend to last longer as well the less stress that was put on them. In terms of longevity, its better to run a system using 200 watts of power 24/7 on a 600 watt power supply vs a 300 watt power supply.

Most systems (outside of distributed computing) does NOT run anywhere close to peak power draw continuously.

Let's take some numbers from AnandTech Bench for a GTX 580.

idle power draw 173W
load power draw Crysis 389W
load power draw Furmark 490W

These are numbers "from the wall" and include the entire system. Unless the only thing you use the computer for is distributed computing or Furmark, on a day-to-day basis the system will likely draw much less power than it is capable of drawing. Crysis is known to draw a lot of power. Other games will likely draw the same, or less. When not gaming, power draw will be a LOT less. Thus, any reasonable quality 450-500W PSU should totally suffice. It should have the juice for the outlier Furmark runs, while having much more power than needed in all other uses.

 

[TemjinGold]

Thanks guys for the responses!

My system at work is a Dell Optiplex MiniTower 990. It has a 265 Watt Gold OEM 80 plus power supply as it was shipped to me.

I want to add a power hungry video card and have already added 16 GB DDR RAM. I see this thing needing 400 to 500 watts if I go by the GPU manufacturer's recommendation.

Problem is with this Dell, which does state it takes a standard ATX power supply, the dimensions are a few mm off in one dimension that would prohibit me from some supplies since the power supplies are not a standard size exactly and Dell has these aluminum case pieces that might have to be bent out of the way.

Is this normal?

Manufacturer recommendation of 400 isn't actually a need of 400. What video card are you trying to get? The likelihood is your system will pull under 300 watts. Not recommending you stay on that puny PSU, mind you. Just saying I doubt you will actually need 400-500 watts.