I'm wondering why so many on the forums are trying to push their very power efficient machines even lower with lots of effort.

People starting from let's say 50W AC @ idle and targeting 30W.

Even assuming 24*365 hours of uptime a year, this 20W saving would mean 175kWh a year. Assuming let's say 10c/kWh, it saves less than 20eur a year.

My point is, most easy way to save energy is start from the most power hungry things, like replacing all incandescent and halogen lights with fluorescents, better house insulation, switching away from oil or electric heating, driving a bicycle and leaving the car at home, etc.

I'm pretty sure SPCR member are well aware of the relatively small difference it makes.
It still a difference though.
I think we do it because we can and because there IS a difference.

I actually find saving power to be fun.
Remembering to turn of everything not needed to save a little bit of power.

It makes a change from the usual overclocking stuff, and people peacocking about their clockspeeds and multipliers and how they've managed to eek another 0.1% performance out of their synthetic benchmarks by fiddling with their memory timings.

So what, it's still free money for doing absolutely nothing!

And, for the PC among us, every tiny little bit helps the planet.

I wish my electricity was that cheap. Last bill I paid was 26c/kWh (if you include taxes). This part of the US sucks for energy costs. I think Hawaii is about the same.

every tiny bit helps.

if only 5 % of the 500 million PC's in the world saved 20 extra watts it would be 400 million watts saved per year in energy.

Some of us are also off the grid.

For many people, quiet and low power computing is as much a hobby as overclocking. It's not so much about whether it's practical, but pushing the limits to see if it can actually be done.

Same goes for fanless systems, you really start to hit a point of diminishing returns. A well designed system cooled by one or two fans can be very quiet from a computer chair a few feet away, so the amount of extra cost and effort that needs to go into a fanless system usually isn't worth the minimal noise reduction. That doesn't mean it isn't fun to try and make it work, though.

More or less the same reasons here, with two being the main ones.

1) Cost. I still live with my parents and thus I don't pay the electricity bill, but they do. Due to this, I try to "contribute" as little to it as possible by using ecobulbs etc. and by trying to reduce the power my computers consume as much as possible without overdoing it.

2) Fun. As others have stated, it may not make a huge difference. Even if the difference is negligible, it's still fun to see how low you can get. I remember I owned a system that I'm sure pulled at least 100W at idle because it was overclocked and filled to the max with hard drives etc. Now, my current box draws less than half of that and still does everything I want it to do. I saved money but didn't really sacrifice anything.

Already done that, I had just the pc left.
At home I have an average consumption of 270W and 100W of those are for feeding the pc.
As you say, I'm going cutting forage from the topmost hungry down.

And there's also the opportunity of learning this whole new world of a way of computing...

My Seasonic PSU saved me about 20W over my old unbranded one. It will have paid for itself before its warranty runs out.

I'm considering getting a 2.5" HDD to replace my current 3.5" HDD. It probably won't pay for itself in 5 years, but it would be an upgrade as well as a power saving. If I'm going to spend the money anyway, may as well spend it on efficiency rather than 100s of Gb I don't really need! That will get me down to about 32W at idle...

Besides, I find energy efficiency an aesthetically pleasing thing in its own right.

less power usage -> less heat produced -> less cooling needed -> less noise...

the S in SPCR stands for SILENCE,

How do we know what is possible if we don't at least try to do the impossible?

Late last year I was sorting through several years of electricity bills and I noticed an obvious trend during our summer months of Dec-Feb. Having read some things about reducing power consumption and having a power meter in hand, I set myself the challenge of reducing our household electricity consumption by 33% for the first quarter of 2008.

In a household of 4 people, it was going to be difficult getting everyone to remember the small changes required to do this, but when our bill for that quarter arrived we had used 54% less than the same time a year before, and 49% less than the best summer quarter for over 5 years.

Not long after this I was asked by my work to put together 8 new PCs to replace their old and dying Celeron (Northwood) and Celeron D (Prescott) based machines. My plan was to try and make sure the new PCs were powerful enough to last at least 4 years, but to not use any more power than the old PCs did.

I've been lurking these forums for about 5 years, so the first place I looked for power consumption figures was SPCR. Using the knowledge I'd gained from SPCR articles, forum threads and other websites, I had an idea of what might be possible. I knew that E8200/G31 with 2Gb DDR2 would be overkill for now, but in 4 years time I figured it would be better than anything AMD had to offer in the same price range.

In any case, I did better than I expected as the total idle wattage of the new PCs was 10% less than that of the old PCs (65w old, 58W new). But, if I knew back then that I should've used a different board with the E8200, there would've been around a 30% saving instead.

Anyways, while these may have merely been personal challenges for me to complete, I think that these ideas can be much further reaching as I'm sure that there are many people lurking the SPCR forums daily, like I was, trying to make a small difference.