Is a 135W CPU like a 135W light bulb?

[Guest]

I probably didn't notice in the past, or they weren't specified, but on modern processors like the Core i7 I noticed that they are listing the wattage.

Does that mean if you get a 135W CPU and keep the computer on for like 10 hours a day, it's like the same thing as keeping on a 135W light bulb all day?

My concern is electricity costs...

Which also brings me to another concern...

If I get a 650W PSU would that cost more than say a 500W? I guess the PSU doesn't use all the power, only when needed, but would it make any significant difference?

 

[Haserath]

Not totally. Both AMD and Intel have power saving features that will save electricity when the processors are idle. Only at full load does the processor actually use close to the 130W specified. You could also undervolt the processor to make it use less electricity, the lowest i7 on LGA 1366(i7 930) could probably use only ~90W at Full load if undervolted.

PSU's are usually more efficient when used at 50% of their potential wattage, so a 650W psu would be best used if you have components that will use ~325W. A few percent of savings isn't that big at 300W, though, since even 5% is only 15W. I would get the 650W, usually they provide more Watts for your dollar(in case you ever need the extra power). Get a PSU from a good company(I've heard Corsair, Thermaltake, Seasonic are good brands, but there are many others). The PSU is the most essential part of the computer, if that fails it could potentially fry the rest of the components.

 

[hunter315]

The wattage ratings of CPUs is their max power consumed, so when at full load a 135W CPU does consume as much power as a 135W light bulb, but it turns all 135W into heat that your system has to get rid of.

Your power supply only draws as much as the system needs divided by its efficiency. A 650W unit will likely cost more than a 500W unit but if your system needs the power you need it, and if the 500W is a low level one and the 650W is 80+ certified the 650W will be significantly better.

If your system needs 400W and your power supply is 80% efficient then your PSU will pull 500W from the wall(400W/80%), if your PSU is an old model and is only 70% efficient you pull 571.4W from the wall(400W/70%). In the end this wont make much of a difference to you, if you leave a computer drawing 500W of power running for 12 hours a day for a whole year you will use 2,190kWh, in my region its about 10cents/kWh so thats $219 of power per year, or about $18 per month. If you have your computer running at normal usage it will drop into power saving mode a lot of the time so you will only draw 200W on average reducing power costs to $87.60 per year or $7.30 per month which isnt a large increase

 

[loneninja]

They list a wattage, but in reality it is a TDP measurement for cooling purposes. Few processors actually consume what they're rated at, and you'll notice multiple models have the same rating but will vary in power consumption.

You've also got to remember that rating is for full load operation, anything less will consume far less power and I think the I7 drops down around 10W while idle.

 

[Computerrock1]

^ as they said, the wattage is more of counter for how much heat dissipation it needs in order for it to run cool and properly

 

[Fetal]

The wattage ratings of CPUs is their max power consumed, so when at full load a 135W CPU does consume as much power as a 135W light bulb, but it turns all 135W into heat that your system has to get rid of.

Your power supply only draws as much as the system needs divided by its efficiency. A 650W unit will likely cost more than a 500W unit but if your system needs the power you need it, and if the 500W is a low level one and the 650W is 80+ certified the 650W will be significantly better.

If your system needs 400W and your power supply is 80% efficient then your PSU will pull 500W from the wall(400W/80%), if your PSU is an old model and is only 70% efficient you pull 571.4W from the wall(400W/70%). In the end this wont make much of a difference to you, if you leave a computer drawing 500W of power running for 12 hours a day for a whole year you will use 2,190kWh, in my region its about 10cents/kWh so thats $219 of power per year, or about $18 per month. If you have your computer running at normal usage it will drop into power saving mode a lot of the time so you will only draw 200W on average reducing power costs to $87.60 per year or $7.30 per month which isnt a large increase

EXCELLENT answer. Brilliant +1000