Higher wattage = higher power usage?

[Shuk]

I'm trying to 'go green' with my next PC build, and I've calculated that I'll be using less than 500 watts in my build. However, I'd rather buy a higher wattage power supply to be safe.

My question: Does buying a higher wattage power supply mean that you are using more power, or can it just serve as a 'buffer'?

 

[rahavsmt]

Buying a higher wattage power supply does not mean that you are using more power, you are only using what your system needs. The extra wattage is not used unless your system needs it, so they can serve as a "buffer".

 

[PC_User]

Buying a higher wattage power supply does not mean that you are using more power, you are only using what your system needs. The extra wattage is not used unless your system needs it, so they can serve as a "buffer".

QFT. The computer will be using the amount of wattage that is required for the system components, no more or less due to the capacity of the PSU itself. The sweet spot for maximum efficiency of PSUs lies between 40-60% of the total PSU capacity.

 

[Zero82z]

I'm trying to 'go green' with my next PC build, and I've calculated that I'll be using less than 500 watts in my build. However, I'd rather buy a higher wattage power supply to be safe.

My question: Does buying a higher wattage power supply mean that you are using more power, or can it just serve as a 'buffer'?

There's no "buffering" going on. A PSU will only draw from the mains what it needs to supply power to the PC. Think of it as the PC itself pulling the power from the wall, and it passes through the PSU on the way in order to be converted to a form the PC can run off of.

 

[Shuk]

Thanks guys, I guess I won't skimp on the wattage. I'll get a 650 to 750 watt PSU for my Core i7 and Radeon 5870 build.

 

[GHarris]

With certain caveats, it (in my view) seems to be the case that higher wattage, higher efficiency (and generally higher quality) and higher price all go hand in hand. So by spending more you'll get a better PSU even for use at your lower wattages*. Though whether that matters or not is a very fair question There are plenty of very-decent-quality, lower cost PSUs out there (Corsair CX400 and up).

*Though (one of the aforementioned caveats), as mentioned by posters above, most PSUs have an efficiency curve which means that, below 50% of their peak output, they are a bit less efficient.

 

[JaguarSKX]

Look for an 80PLUS certified PSU which are basically guaranteed to be at least 80% efficient for any load placed on the PSU.

There are also "Bronze", "Silver" and "Gold" standards for 80PLUS. The higher the standard means higher minimum efficiency; 82%, 85% and 87% respectively. Generally speaking, the higher the "metal" standard, the higher the price.

I really don't consider an i7 CPU and HD 5870 as "going green" unless you are gonna try to power it by peddling one of those stationary excerise bicycles.

 

[Shuk]

Well I'm not going to neuter my system in order to make it use less energy. Going green means more efficiency and less waste, not less performance.

 

[vjcsmoke]

Well I'm not going to neuter my system in order to make it use less energy. Going green means more efficiency and less waste, not less performance.

Just get an 80+ certified PSU. It's worth spending a little more to get a more efficient PSU, as over the long run the energy savings will pay for itself. There are a lot of "green" hard drives out there that consume little power and are ideal for storage, and LED backlight monitors like the G2410 will also save you electricity as well. The other cool thing is that SSDs (solid state drives) are energy efficient and also offer superior performance as a boot or gaming drive.