To put wattage needs in perspective

EarthDog said:

It is more than enough. Stock 7870s are 175w cards. You could easily add the cpu in there as well and even overclock a bit.

People tend to overestimate quite a bit on how much they really need.

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OTOH it's better to run well under the max rating than push it to the limits.

I recently got a used PCP&C Quad 750 for my main/GPU folding rig, but decided to keep it in reserve for my next project. I'd love to build a 2P Xeon or 4P Opteron workstation one of these days.

It is, but not to the point that some people do. I have seen, several times here, people mention this 50% number being good. If you are going SLI/CFx then sure, you need the headroom. If you aren't and go 50%ish, its waste of cash.

While I would never do it, a quality PSU should run its rating for its warrantied life. I prefer to stick around 75% or so. The PSUs I choose are very efficient so running at that capacity it is still whisper quiet (EVGA Supernova G2 750W). And I saved $50 in doing so.

People always overestimate their power needs.

petteyg359 said:

And that is why we have a world that doesn't give a **** about the world - because it's all about the immediate price in dollars. But, for an older system with a < 90% efficient PSU, it will pay for itself within the warranty period unless you have a below-average per-kWh price.

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I still highly doubt that the cost savings of the efficiency would work out to be equal.

Looking at the Corsair AX1500i 80+Titanium PSU which costs $400 or the ST1500 Silverstone 80+Silver power supply (which received a 9.7 on JG) for $270. You get approximately 94% efficiency at the 50% mark on the titanium and 89% on the Silver. I pay $0.06/kwh on my electricity.

With the efficiency of the AX1500i running at 750W you are wasting approximately 47.8w. If running at 100% of the time at 750W (.0478*720*6) Which according to my calculations = $2.06/mo
With the efficiency of the ST1500 running at 750W you are wasting approximately 90w. (.090*720*6) Which = $3.88/mo

Leaving $1.82 difference in cost savings of the Titanium PSU for month. In order to make up the difference of the two power supplies ($130) it would take approximately 135months or a little over 11 years.

Even looking at Corsair's webpage of savings for a more efficient PSU:
http://www.corsair.com/en-us/blog/2...at-does-it-mean-and-what-is-the-benefit-to-me

It has a cost savings of $5/year with a Platinum over the Silver. Granted that doesn't cover Titanium, but the difference is still going to be less than $10.

petteyg359 said:

And that is why we have a world that doesn't give a **** about the world - because it's all about the immediate price in dollars. But, for an older system with a < 90% efficient PSU, it will pay for itself within the warranty period unless you have a below-average per-kWh price.

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You may want to work out the math on that one petty (ive done it before). Unless you f@H or mine bitcoins or game 12 hours /day 365 days /year, you won't get it back unless your electric costs are incredibly high. Gaming 4 hours a day, IIRC, doesn't do it either.

But a miner/folder someone that runs under load 24/7 or close to it, I'm with you.

EarthDog said:

You may want to work out the math on that one petty (ive done it before). Unless you f@H or mine bitcoins or game 12 hours /day 365 days /year, you won't get it back unless your electric costs are incredibly high. Gaming 4 hours a day, IIRC, doesn't do it either.

But a miner/folder someone that runs under load 24/7 or close to it, I'm with you.

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So I dun good with my EVGA 850G then.