Re-using heat from PC's?

[imported_Tick]

Originally posted by: CTho9305

Originally posted by: Tick
People worry so much about the energy their computer uses, but it's important to remember how trivial the energy it uses is. And average computer dissipates maybe 100w. So does that 100w lightbulb you've got. Both are trivial expenditures of energy. It's only on industrial and corporate scales that computer power usage is significant.

Do you really have that many 100W lights? I think a single bulb in my place was 100W (halogen torchiere)... none are now because they're all CFLs (so even my 4-bulb ceiling fans only burn 52W when lighting a room).

Yeah, I'm gradually replacing my bulbs with CFLs. But I always buy 100w in incan. I like a lot of light, and the color temp. is usually better.

 

[imported_Tick]

Originally posted by: BrownTown

Originally posted by: DrPizza
But, that 300 watt power supply isn't really using 300 watts all the time.

Yes, but like I said, low end computer is 300W power supply, high end up 600W power supply, so low end computer might use 200W while on and high end might use 400W. Both numbers are much larger than 100W.

Your still a bit high from what I've seen. If someone has real world data, I'd love to see it.

 

[foges]

Originally posted by: Tick

Originally posted by: BrownTown

Originally posted by: DrPizza
But, that 300 watt power supply isn't really using 300 watts all the time.

Yes, but like I said, low end computer is 300W power supply, high end up 600W power supply, so low end computer might use 200W while on and high end might use 400W. Both numbers are much larger than 100W.

Your still a bit high from what I've seen. If someone has real world data, I'd love to see it.

Look at the table at the bottom of this page, seems like even at close to full cpu usage the computer did not need more than slightly over 150W: http://www.silentpcreview.com/article188-page3.html

Note: the system used was not very high end.

 

[herm0016]

how about hooking a sterling engine to a water cooling setup to run a fan over your rad? or just a sterling engine to run a fan in the pc somewhere using the heat of the proc. the larger the temp difference the faster it will spin too, sort of a self regulating thing. hmm... this sounds like a neat project.

 

[imported_Baloo]

Originally posted by: CTho9305

Originally posted by: firewolfsm

Originally posted by: CTho9305
FYI, 100% of the energy that your computer uses ends up heating up your room.

A lot of the energy is mechanical, some is used as light or sound.

And what happens when the photons from the LEDs hit your wall and reflect a couple of times? What do the sound vibrations end up as? When the hard drive is spinning, the motor uses energy to overcome friction - what is friction turning the rotational energy into? It all ends up as heat. Unless you're shooting an significant amount of light out a window, it's all heating up your room.

Your figure is way off. If it were 100%, there'd be no energy to run the pc - it'd all be dissipated as heat before it could. An active PFC PSU is about 80% efficient. That leaves 20% dissipated as heat by the PSU. The PC itself is going to vary, but usually is less wasteful than the Power supply. Worst case my guess would be 50% total dissipated as heat. I be willing to wager the average is much less than that.

 

[f95toli]

No, all the energy is ultimately transformed into heat. Efficienty is just a measure how much of the energy can be used for something "useful" before it is lost; if 50% is lost as heat that means that 50% can be used to do work, However, that 50% will THEN be converted into heat when it is used (e.g. the CPU heats up).
Remember that you can never destroy or create energy; the energy that goes into your computer must go somewhere and since a computer is the "end of the road" (it is not transfering energy to something else) this something is heat. Hence, "running the PC" means converting electrical energy into heat.

 

[CTho9305]

Originally posted by: Baloo

Originally posted by: CTho9305

Originally posted by: firewolfsm

Originally posted by: CTho9305
FYI, 100% of the energy that your computer uses ends up heating up your room.

A lot of the energy is mechanical, some is used as light or sound.

And what happens when the photons from the LEDs hit your wall and reflect a couple of times? What do the sound vibrations end up as? When the hard drive is spinning, the motor uses energy to overcome friction - what is friction turning the rotational energy into? It all ends up as heat. Unless you're shooting an significant amount of light out a window, it's all heating up your room.

Your figure is way off. If it were 100%, there'd be no energy to run the pc - it'd all be dissipated as heat before it could. An active PFC PSU is about 80% efficient. That leaves 20% dissipated as heat by the PSU. The PC itself is going to vary, but usually is less wasteful than the Power supply. Worst case my guess would be 50% total dissipated as heat. I be willing to wager the average is much less than that.

The energy used to "run" the PC ends up as heat. When a logic gate switches, it either charges a capacitor up to the supplied voltage, or discharges it to zero. After two switches, some unit of charge has been carried from the supply to ground, which comes out as heat. Computation doesn't really count as work like lifting something does...all the energy that goes in ends up as heat. If you want to think about it with a more physical example, it's like taking buckets of water from a higher-altitude lake and lowering them to sea level (or dumping them over the edge of a dam). The potential energy the water had from its initial altitude gets converted to kinetic energy as it falls, but when it hits the bottom it all ends up as heat.

If you drive a car around the block once, all the energy ends up as heat. For a while, the car is moving, so there's kinetic energy, but when the car comes to a stop, that kinetic energy has all been converted to heat.

 

[videogames101]

On a personal basis, i really do use my comp to heat my room, and in the winter it's the warmest in the house.

So, I have no reason to believe couldn't be done on large scales.

 

[jagec]

Originally posted by: Tick

Originally posted by: BrownTown

Originally posted by: DrPizza
But, that 300 watt power supply isn't really using 300 watts all the time.

Yes, but like I said, low end computer is 300W power supply, high end up 600W power supply, so low end computer might use 200W while on and high end might use 400W. Both numbers are much larger than 100W.

Your still a bit high from what I've seen. If someone has real world data, I'd love to see it.

I read an article a while back, but now I can't find the link. Here's another link,though.

Using the Kill-A-Watt meter, he got 118 watts idle, 172 watts full load, for the following system:
* Athlon X2 4800+
* GeForce 6600 video
* Maxtor 300gb SATA HDD
* GeForce 5200 PCI video (for 3rd display)
* 2gb PC3200 DDR RAM
* generic DVD-ROM

The other article also confirmed that we're paying WAY too much for high-wattage power supplies. True, you don't want to run your power supply near 100%, but how much do you want to bet that the power supply for the rig in the link if well over a 300W?

Obviously PSU quality is a bigger issue, though...all the spare watts in the world won't help if one of your lines drops below a voltage the computer's happy with.

Another link, to a forum where people are posting the most they've run on a 300W PSU.

There's also my Dell, with a 305W PSU running:
P4 3GHz Prescott --yes the hot ones. I'm planning on pin-modding it to 4GHz.
2x1GB DDR2
Radeon x850xt pe @ 640/630
74GB Raptor
500GB Seagate 7200.10
DVD burner
wireless NIC, fans.