I went to the OC forums and Tom's hardware looking for an answer to this, and both threads ended up arguing about it with no clear answer.
So I ask you /g/,
Does a 1000w PSU draw more than required to power a PC?
and if not,
Is a 1000w PSU more efficient?
>Is a 1000w PSU more efficient?
Depends. Different PSU have different efficiency in different wattage ranges
>Does a 1000w PSU draw more than required to power a PC?
No. It doesn't draw 1000w if your CPU needs 450w, if that's what your asking.
Doesn't matter.
A PSU's efficiency changes based on load.
Get the most efficient PSU.
>>52487831
Efficiency is usually best when the PSU is operating close to half of its max rated output, as in pic related.
So if your PC typically draws 500W, a 1000W PSU will have good efficiency. If your PC typically draws 100W, a 1000W PSU will have lower efficiency.
PSUs are most efficient at around 50% load. If maximum efficiency is your goal, the highest-rated PSU you can get that's roughly double your system's actual power consumption is the way to go.
A PSU will not supply for power than your PC needs at a given moment
In theory, to supply 300 W to your system, a 1kW unit will draw the same amount of power as a 300W power. But that is only strictly true if both units have the same power efficiceny at 300W
For each unit, it's efficiency differs at different power loads. Usually a unit will be the most efficient at its rated wattage. Look up the requirements for the various levels of 80+ certification for details. And also look up JonnyGuru measurements of the unit in question. Sometimes a unit will be better than required. This is especially true for the all-out ridiculously high-grade platinum units.
>>52487871
Getting such a huge wattage PSU is kinda stupid though. The sweetspot is somewhere @ 70-80% desu.
>>52487877
>Usually a unit will be the most efficient at its rated wattage
I'm retarded. The others are right about 50%
What I should have said is that matching your PSU rated power to your system's peak requirement is a good rule of thumb because your system will not be a full load most of the time and PSU makers take account of this
60%
is better
though 50% is a waste but then again 50% load means as the powersupply gets older its drops voltage meaning you can use your PSU for longer but usually PSU burn out when there is a power spike during a lighing storm or your capitors blow up or voltage step down regulator gets broken
so PSU's rarelly live up to the long life hype.
I have a safety swich on mine but its still nothing compeared to lighting strike.
>>52487887
Not really. There's just not that much difference between the price of an 850W unit compared to a 650W one. You might as well just buy the larger one, enjoy the efficiency and have plenty of room to upgrade to SLI/Crossfire in the future if you so choose.
Not to mention the silence on a semi-passive unit. I have a 750W unit with a semi-passive mode and the fan almost never spins up because I don't work it that hard. And it didn't cost any more than a lower wattage fully passive model.
>>52487973
1000w ones are quite more expensive than 650w for example and if you're gonna have 500w max under load it means you probably have even less doing random shit
no
:^)
>>52487831
No.
That's why efficiency ratings exist. A platinum/gold/silver/etc PSU will never drop below a certain efficiency regardless of load.
In its most efficient state it might 5% better. It's not worth wasting your time thinking about it.
>>52487831
>Does a 1000w PSU draw more than required to power a PC?
If your system wants 500w, that's how much it will draw no matter what PSU is behind it, however efficiency does add on top of the power draw. 500w power draw on a 90% efficient PSU will result in 550w at the wall.
Some potential benefits:
- higher wattage supplies typically use higher-grade components
- output degrades slightly over years of operation, especially on 24/7 systems
- certain high-output PSUs don't spin the fan on until they hit a high enough load level
That said, you do not need more than a 650~750w PSU even for an overclocked X99 system with 980 TI and a bunch of drives, and a 1kw PSU is pretty much for SLI only.
>>52487831
I got myself a corsair 850rm because it costed me as much as the 650w psu I was planning to get in some crazy offer. Actually the semi passive thing is quite a nice feature so I would recommend to look if there happens to be stone offer where you can get a slightly bigger psu than you need so you have the option to upgrade parts later. Another nice thing to have is the longer warranty most higher wattage units have this however depends in where you lube since warranty polices vary from country to country.
>>52487831
power supplies are most efficient being loaded 60% to 80% of their capacity
so yes, a 1000w power supply is less efficient than say a 650w if youre only drawing 500w
