Too much wattage???

[Pacwageo]

Ok so I was in the Mobo subforum and I posted the specs of my computer. I've determine that I made a mistake by purchasing a 700W power supply. My system simply does not call for that much wattage consumption. I thought I was doing myself a favor by giving myself some leg room in the future, however I'm thinking that not a lot people agree with me.

System specs:

Proc: X2 6000+ (3.0GHz)
RAM: 4GB DDR2 800
HDD: 2x 250GB WD
Mobo: Asus M2N SLI Capable (lots of features )
Extras: 1x DVD CD All-in-one drive SATA
Vid Card: 1x SAPPHIRE Radeon X1650PRO 256MB 128 Bit (Not running any SLI atm)

And of course... my giant 700W PSU lol.

My question is... will this giant PSU cause problems for my system? I dont think it will but I figure I should ask before i turn it on.

My second question is... did I waste my money on this PSU? Even lets say I do upgrade to an SLI vid system on this same mobo?

Thanks for your input... I know they are newb questions. I havnt built a system in a while.

 

[Spawn85]

You definitely don't NEED that much wattage. You'll be able to run that system with a 520W easily with amps to spare. However, you may want to upgrade your vid card in the future etc or whatever. Even then you'll have more than enough with a 700W. who knows maybe you'll want to run like 10 hard drives and 3 PCIe cards.

Until then, enjoy paying extra on your electricity bill for the unused watts.

 

[Trepidati0n]

Considering you can run a quadcore and a 8800GTX/Ultra on a 500W PSU no problems...I think you are okay. Nothing wrong with headroom.

 

[Trepidati0n]

Until then, enjoy paying extra on your electricity bill for the unused watts.

What are you talking about? He pays nothing "extra" on his bill. Just because a PSU is 700W doesn't mean it is always consuming 700W.

 

[rsgunter]

What are you talking about? He pays nothing "extra" on his bill. Just because a PSU is 700W doesn't mean it is always consuming 700W.

Indeed.

Also, a 520w is too much for that system if you really want to crunch numbers. But yeah man, nothing wrong with headroom, and if you ever see someone needing a big power supply, sell them yours and make some money.

 

[Michael Daly]

What are you talking about? He pays nothing "extra" on his bill.

Well, there is the possibility that he's operating outside the optimal output for the PSU. Since efficiency is not constant with output, if you are consistently well over or under the peak efficiency load, the electric bill will be higher than it should be. This, of course, will be a modest difference - it would matter if you were running a server farm 24/7, but not much for one machine used a few hours a day.

 

[Farva]

There is never such a thing as too much wattage. Your computer only uses the amount you need.

 

[Pacwageo]

That makes me feel a little better about my situation lol. Ya i didnt think there would be a problem. By the way, if you need a 700W PSU the Tagan series are very nice looking in almost any case I've seen. Ive read nothing but good reviews about their performance.

Thanks everyone for all the comments. Much appreciated.

 

[bassgoonist]

Well, there is the possibility that he's operating outside the optimal output for the PSU. Since efficiency is not constant with output, if you are consistently well over or under the peak efficiency load, the electric bill will be higher than it should be. This, of course, will be a modest difference - it would matter if you were running a server farm 24/7, but not much for one machine used a few hours a day.

All psu tests I have ever seen show the effeciency going up or remaining constant at lower wattages. Its really simple, the less percent of maximum draw, the higher the efficiency. These tests went only as low at 25% load, but seriously, how could you run a computer with only 250 watts (25% of 1000watts). If you have a modern graphics card and cpu you'll probably never get below 250.

 

[Redbeard]

All psu tests I have ever seen show the effeciency going up or remaining constant at lower wattages. Its really simple, the less percent of maximum draw, the higher the efficiency. These tests went only as low at 25% load, but seriously, how could you run a computer with only 250 watts (25% of 1000watts). If you have a modern graphics card and cpu you'll probably never get below 250.

This is actually close to true, with a few caveats.

Check out this graph:

Most high end PSUs with good efficiency have an efficiency curve. This means that there's a "sweet spot", usually between 30-80% of max output, that is where the PSU pushes its maximum efficiency.

Which means if you buy a 700W PSU, and have low-power components that require less than 30% of the max load (210W or less), the efficiency will be significantly lower. It may not add up to much, unless you leave your system on all the time all year round.

But the difference between peak efficiency of, say, 85% or so, and let's say 77% efficiency at 10-15% of output, can be a decent amount. If you drop 8% efficiency, and are down around 150W, leaving it on 24/7, you can cost yourself an extra $20-30 a year depending on what electricity bills are in your area.

This can make the case for matching the needs of your system to the efficiency curve, if you really use your system a lot.

So while this answer is pretty long, the breakdown is: you should be fine with a 700W PSU and that system, but you may end up paying a bit more in electricity bills, depending on how much you use it. For your system, a 450-550W PSU would be the best, I think, hitting your power needs in the peak efficiency curve range.

To give you an idea of low power systems, check this config out:
Core 2 Duo E6300
Asus P5K motherboard
nVidia 7600GT GPU
Sound Blaster X-Fi
2GB Corsair RAM
4x 500GB SATA HDD
Corsair VX450W PSU

Max power that thing draws, at full load, is 220W from the wall, which means that at ~80% efficiency, we're only drawing between 176W-185W from the PSU.

 

[bassgoonist]

Hmm yeah, I was a bit off, maybe I should double check before I post :-p

 

[Spawn85]

What are you talking about? He pays nothing "extra" on his bill. Just because a PSU is 700W doesn't mean it is always consuming 700W.

I was referring to the effect of using the PSU below efficiency (which may or may not be the case here). See Redbeards post.

 

[[Spectre]]

That being said you aren't going to notice a 2% in efficiency on your electric bill if you have anything else running in your home.

 

[Redbeard]

That being said you aren't going to notice a 2% in efficiency on your electric bill if you have anything else running in your home.

I have a USB Dishwasher, Clothes Dryer, Television, and Circular Table Saw! Everything in my house runs off my PSU!

Seriously though, you're right, but once you get to 7-8% the difference can be a couple bucks a month. Which isn't huge, obviously, but it does exist.

 

[Pacwageo]

So basically, my system mentioned below will be extremely inefficient when run on a 700W PSU? Is it possible that my system would consume the ideal 40% of the 700W available? According to the chart above my system would only need to consume 300W to be at an approximate 42% consumption. In my opinion this would be ideal.

Proc: X2 6000+ (3.0GHz)
RAM: 4GB DDR2 800
HDD: 2x 250GB WD
Mobo: Asus M2N SLI Capable
Other: 1x DVD CD All-in-one drive SATA
Vid Card: 1x SAPPHIRE Radeon X1650PRO 256MB 128 Bit (Not running SLI atm)

 

[Nenu]

I wouldnt worry about it.
The efficiency curve does count but if its a new good brand PSU, the change in efficiency at idle power (I'm assuming 120 Watts+) wont bother you as its only a few % difference.

On that chart the max efficiency deviation for either PSU is only 3%, so lets assume it deviates to 5% at 120watts utilised, therefore using about 6W more.
In the UK that would cost about £6 a year to run an extra 6W permanently.
Its even cheaper in the US.

If you were to use say a 600w PSU with the same efficiency ratings per % of max power utilised, you might get 0 to 2% better efficiency at idle.
Its a good idea to have at least a 600W PSU these days for when you upgrade so you've done ok.

For comparison, my system is
A64 x2 @ 2.8GHz, 2x1GB DDR, X1800PE, Audigy 4, 3 hard drives and a DVD drive.
PSU = Hiper 580W

Measured at the mains socket, it uses:
135 Watts idle with no hard drives powered up (power saving)
155 Watts idle with all 3 hard drives powered up
287 Watts full load (3DM2006) with all 3 hard drives powered up

 

[andyOCZ]

This is all very good info, but basically don't worry about it. The money you save by not having to upgrade your PSU in the near future should offset any minuscule additional costs to run your PC with a larger PSU. See how easy that was?